LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 


Class 


GENERAL  SPECIFICATIONS   FOR 
STRUCTURAL   WORK   OF. 
BUILDINGS. 

BY 

C    C.  SCHNEIDER,  M.  Am.  Soc.  C  E. 


NEW     YORK: 

THK  ENGINEERING  NEWS  PUBLISHING  COMPANY. 
1910. 


GENERAL    SPECIFICATIONS    FOR 

STRUCTURAL  WORK  OF 

BUILDINGS. 


BY 


C.  C.  SCHNEIDER,  M.  Am.  Soc.  c.  E. 


Of   THE 

UNIVERSITY 

OF 

LUFOR] 


^ 

(• 

c 


COPYRIGHTED  1910  BY 
C.  C.  SCHNEIDER. 


OF  THE 

UNIVERSITY 

OF 
£4  L I  FOR] 


PREFACE. 


This  edition  of  the  General  Specifications  for  Structural  Work  of 
Buildings  is  a  reprint  from  the  one  published  in  Transactions  of  the 
American  Society  of  Civil  Engineers,  Vol.  LIV,  page  490  (1905),  re- 
vised to  date.  It  contains  additional  tables  and  other  useful  informa- 
tion, also  specifications  for  concrete  and  reinforced  concrete  for  build- 
ing construction. 

As  reinforced  concrete  construction  has  lately  come  into  extended 
use  for  building  work,  the  writer  thought  it  expedient  to  include  a  set 
of  regulations  covering  its  essential  requirements,  based  on  what  he 
considers  safe  practice. 

In  preparing  specifications  for  reinforced  concrete,  the  writer  has 
been  guided  by  those  already  in  existence,  the  most  prominent  of 
which  are  the  regulations  of  the  French,  Prussian,  Austrian  and  Swiss 
Governments,  the  Association  of  German  Architects  and  Engineers, 
the  German  Concrete  Association,  and  those  proposed  by  a  joint  com- 
mittee of  the  British  Architectural  and  Building  Associations  and  the 
Government  Bureaus  and  the  recommendations  of  the  Special  Com- 
mittee on  Concrete  and  Reinforced  Concrete  of  the  American  Society 
of  Civil  Engineers,  with  such  modifications  as  have  been  suggested 
by  experience  and  the  lessons  taught  by  failures. 

For  that  part  of  the  specifications  covering  aggregates,  preparation 
and  placing  of  concrete  and  mortar,  the  recommendations  of  the 
Special  Committee  on  Concrete  and  Reinforced  Concrete  of  the  Ameri- 
can Society  of  Civil  Engineers  have  been  adopted  as  representing  the 
best  modern  practice. 

C.  C.  SCHNEIDER. 

PHILADELPHIA,  PA.,  May,  1910. 


206530 


CONTENTS. 


GENERAL  SPECIFICATIONS  FOR  STRUCTURAL 
WORK    OF    BUILDINGS. 


DESIGN. 

LOADS 7-9 

UNIT  STRESSES  AND  PROPORTION  OF  PARTS   9-12 

Substructure,  Unit  Stresses 9, 10 

Masonry  Pillars  and  Walls 10-12 

Steel  Superstructure,  Unit  Stresses 12-14 

Cast  Iron 14 

Timber 14 

Details  of  Steel  Construction 14-18 

MATEEIAL    AND    WOEKMANSHIP. 

MATERIAL 18-21 

Rolled  Steel 18-21 

Steel  Castings 19,  20 

WORKMANSHIP 21-24 

Shopwork 21-24 

Painting 24 

Inspection  and  Tests 24,  25 

Full-sized  Tests 25 

CONCRETE   AND  REINFORCED   CONCRETE. 

PROPER  USE  OF  CONCRETE 27 

IMPROPER  USE  OF  CONCRETE 27-29 

RESPONSIBILITY  AND  SUPERVISION 29,  30 

SPECIFICATIONS  FOR  PLAIN  AND  REINFORCED  CONCRETE  CON- 
STRUCTION    31-41 

Design  .  ; 31-35 

General  Assumptions  for  Static  Computations 32 

External  Forces 32 

Internal  Forces 32,  33 

Working  Stresses 33,  34 

Details  of  Construction 35,  36 

MATERIALS  AND  WORKMANSHIP 36 

Aggregates 36,  37 

Steel 37 

Concrete 37-40 

Inspection  and  Tests 40,  41 

FORMULAS  FOR  APPROXIMATE  COMPUTATIONS.  .                           .  42-44 


APPENDIX. 
CONSISTING  OF  THE  FOLLOWING  TABLES  : 

PAGE 

1. — Weights  of  Building  Materials,  etc 45 

2. — Weights  of  Merchandise,  etc 45 

3. — Permissible  Compressive  Strain 46 

4. — Shearing  and  Bearing  Value  of  Kivets ,  47 

5. — Maximum  Bending  Moments  on  Pins 48 

6. — Thickness  of  Spruce  and  White  Pine  Plank  for  Floors 48 

7. — Standard  Dimensions  of  Columns 49 

8. — Standard  Beam  Framing 50 

Separators 50 

Cast-Iron  Washers 50 

9.— Standard   Details 51 

10.— Plate   Girders 52 

11.— Weights  of  Eoof  Trusses 53 

12. — Dimensions  of  Typical  Hand  Cranes 53 

13. — Dimensions  of  Typical  Electric  Traveling   Cranes 54 

14. — Abstracts  from  Building  Laws 55-68 


GENERAL 


SPECIFICATIONS  FOR  STRUCTURAL 
WORK  OF  BUILDINGS. 


DESIGN. 
LOADS. 

1.  The  "dead"  load  in  all  structures  shall  consist  of  the  weight    Dead  Load, 
of  walls,  floors,  partitions,  roofs  and  all  other  permanent  construction 

and  fixtures. 

2.  In  calculating  the   "dead"  loads,   the  weights   of  the  different 
materials  shall  be  assumed  as  given  in  Table  1. 

3.  The  minimum  weight  of  fire-proof  floors  to  be  assumed  in  de- 
signing the  floor  system  shall  be  75  Ib.  per  sq.  ft.     For  columns,  the 
actual  weight  of  floors  shall  be  used. 

4.  For   office   buildings,   10  Ib.   per  sq.   ft.   of  floor   area   shall  be 
added  to  the  dead  load  of  the  floor  for  movable  partitions. 

5.  The  following  table  gives  the  "live"  load  on  floors,  to  be  as- 
sumed for  different  classes  of  buildings.     These  loads  consist  of: 

a. — A  uniform  load  per  square  foot  for  floor  area; 
b. — A  concentrated  load  which  shall  be  applied  to  any  point 
of  the  floor; 

c. — A  uniform  load  per  linear  foot  for  girders. 
The  maximum  result  is  to  be  used  in  calculations. 
The    specified    concentrated    loads    shall    also    apply    to    the    floor 
construction  between  the  beams  for  a  length  of  5  ft. 

TABLE  OF  LIVE  LOADS. 


Live  Load 
on  Floors. 


Classes  of  buildings. 

LIVE  LOADS,  IN  POUNDS. 

Distributed 
load. 

Concentrated 
load. 

Load  per  linear 
foot  of  girder. 

Dwellings,  hotels,  apartment-houses,  dormi- 
tories, hospitals. 

40 
50 

60 

80 

I      floor  100 
C  columns  50 

80 
300 
from  120  up 
"     300  u 

( 
"     200   "J 

2  000 
5  000 

5  000 

5  000 

j-        5  000 

8  000 
10  000 
Special. 

The  actual  t 
gines,  boilers, 
shall  be  used,  1 
less  than  200  It 

500 
1  000 

1  000 
1  000 

1  000 

1  000 
1  000 
Special. 

weights  of  en- 
stacks,   etc., 
jut  in  no  case 
.  per  sq.  ft. 

Office  buildings,  upper  stories  

Schoolrooms,  theater  galleries,  churches  

Ground  floors  of  office  buildings,  corridors 
and  stairs  in  public  buildings 

Assembly  rooms,   main  floors  of    theaters, 
ballrooms,  gymnasia,  or  any  room  likely 
to  be  used  for  drilling  or  dancing  

Ordinary  stores  and    light  manufacturing, 
stables  and  carriage-houses 

Sidewalks  in  front  of  buildings.   . 

Warehouses  and  factories  

Charging  floors  for  foundries  

Power-houses,  for  uncovered  floors  

8 


Crane  Loads 
and  Impact. 


Live  Loads 
on  Flat 
Roofs. 


Wind 
Pressure. 


Live  Loads 
on  Roofs. 


Loads  on 
Ordinary 
Roofs. 


6.  If  heavy  concentrations,   like  safes,   armatures,   or  special  ma- 
chinery,   are   likely   to    occur    on    floors,    provision    should   be    made 
for  them. 

7.  For   structures   carrying   traveling   machinery,    such   as   cranes, 
conveyors,   etc.,   25%    shall  be   added  to   the   stresses   resulting   from 
such  live  load,  to  provide  for  the  effects  of  impact  and  vibrations. 
(For  crane  loads,  see  Tables  12  and  13.) 

8.  Flat    roofs    of    office   buildings,    hotels,    apartment-houses,    etc., 
which  can  be  loaded  by  crowds  of  people,  shall  be  treated  as  floors, 
and   the   same   distributed  live  loads   shall   be   used   as   specified   for 
hotels  and  dwelling-houses. 

9.  The  wind  pressure   shall  be   assumed   acting   in   any   direction 
horizontally : 

First.— At  20  Ib.  per  sq.  ft.  on  the  sides  and  ends  of  buildings 
and  on  the  actually  exposed  surface,  or  the  vertical  projection 
of  roofs; 

Second. — At  30  Ib.  per  sq.  ft.  on  the  total  exposed  surfaces 
of  all  parts  composing  the  metal  framework.  The  framework 
shall  be  considered  an  independent  structure,  without  walls,  par- 
titions or  floors. 

10.  Roofs  shall  be  proportioned  to  carry  in  addition  to  their  own 
weight  the  following  live  loads: 

a. — A  snow  load,  per  horizontal  square  foot  of  roof,  of  25 
Ib.  for  all  slopes  up  to  20°;  this  load  to  be  reduced  1  Ib.  for 
every  degree  of  increase  in  the  slope  up  to  45°,  above  which  no 
snow  load  is  considered. 

b. — A  wind  load  as  specified  in  paragraph  9. 

The  possibility  of  a  partial  snow  load  has  to  be  considered. 

The  above  loads  given  for  snow  are  the  minimum  values  for  locali- 
ties where  snow  is  likely  to  occur.  In  severe  climates  these  snow 
loads  should  be  increased  in  accordance  with  the  actual  conditions 
existing  in  those  localities.  In  tropical  climates  the  snow  loads  may 
be  neglected. 

11.  In  climates  corresponding  to  that  of  New  York,  ordinary  roofs, 
up  to  80  ft.  span,  shall  be  proportioned  to  carry  the  following  mini- 
mum  loads,   per   square   foot   of   exposed   surface,    applied   vertically, 
to  provide  for  dead,  wind  and  snow  loads  combined: 


9 


Slate : 


Gravel  or      C     On  boards,  flat  slope,  1  to  6,  or  less.  ..  .50  Ib. 
Composition    J     On  boards,  steep  slope,  more  than  1  to  6.  .45  " 

Roofing:       (     On  3-in.  flat  tile  or  cinder  concrete 60  " 

Corrugated  sheeting,  on  boards  or  purlins 40  " 

On  boards  or  purlins 50  " 

On  3-in.  flat  tile  or  cinder  concrete 65  " 

Tile,  on  steel  purlins 55  " 

Glass    45  " 

12.  For  roofs  in  climates  where  no  snow  is  likely  to  occur,  reduce 
the  foregoing  loads  by  10  Ib.  per  sq.  ft.,  but  no  roof  or  any  part  thereof 
shall  be  designed  for  less  than  40  Ib.  per  sq.  ft. 

13.  For  columns,  the  specified  uniform  live  loads  per  square  foot 
shall  be  used,  with  a  minimum  of  20,000  Ib.  per  column. 

14.  For  columns   carrying  more  than  five  floors,  these  live  loads 
may  be  reduced  as  follows: 

For  columns  supporting  the  roof  and  top  floor,  no  reduction; 

For  columns  supporting  each  succeeding  floor,  a  reduction  of 

5%   of  the  total  live  load  may  be  made  until  50%   is  reached, 

which  reduced  load  shall  be  used  for  the  columns  supporting  all 

remaining  floors. 

This  reduction  is  not  to  apply  to  live  load  on  columns  of  ware- 
houses, and  similar  buildings  which  are  likely  to  be  fully  loaded  on 
all  floors  at  the  same  time. 

15.  The  live  loads  on  foundations  shall  be  assumed  to  be  the  same 
as  for  the  footings  of  columns.    The  areas  of  the  bases  of  the  founda- 
tions shall  be  proportioned  for  the  dead  load  only.     That  foundation 
which  receives  the  largest  ratio  of  live  to  dead  load  shall  be  selected 
and  proportioned  for  the  combined  dead  and  live  loads.     The  dead 
load  on  this  foundation  shall  be  divided  by  the  area  thus  found,  and 
this  reduced  pressure  per  square  foot  shall  be  the  permissible  working 
pressure  to  be  used  for  the  dead  load  of  all  foundations. 

UNIT  STRESSES  AND  PROPORTION  OF  PARTS. 
Substructure. 

16.  Pressure  on  foundations  not  to  exceed,  in  tons  per  square  foot: 

Soft    clay 1 

Ordinary  clay  and  dry  sand  mixed  with  clay 2 

Dry  sand  and  dry  clay 3 

Hard  clay  and  firm,  coarse  sand 4 

Firm,  coarse  sand  and  gravel .  .  6 


Live  Loads 
on  Columns. 


Reduction  of 
Live  Load 
on  Columns. 


Loads  on 
Foundations. 


Foundations. 


10 

Masonry.  17.  Working  pressure  in  masonry  not  to  exceed  the  following: 

Tons  per       Lb.  per 
sq.  ft.  sq.  in. 

Common  brick,  Portland-cement  mortar 12  168 

Hard-burned  brick,  Portland-cement  mortar....  15  210 

Rubble  masonry,  Portland-cement  mortar 10  140 

Coursed    rubble,    Portland-cement    mortar 12  168 

First-class   masonry,    sandstone 20  280 

"        "  "          limestone  or  bluestone 25  350 

"        "  "          granite 30  420 

Concrete  for  walls: 

Portland    cement   1:2:5 20  280 

"  "          1:2:4 25  350 

Pressure  of  18.  The  pressure  of  beams,  girders,  wall-plates,  column  bases,  etc., 

on  masonry  shall  not  exceed  the  following,  in  pounds  per  square  inch : 

On  brickwork  with  cement  mortar 300 

"    rubble  masonry  with  cement  mortar. 250 

"   Portland-cement  concrete  1:2:4 600 

"    first-class  sandstone  (dimension  stone) 400 

"       "      "    limestone  500 

«        "       "    granite   600 

Bearing  19.  The  maximum  load  carried  by  any  pile  shall  not  exceed  40,000 

Timber  Piles.   lb.,  or  600  lb.  per  sq.  in.  of  its  average  cross-section. 

Piles  driven  in  firm  soil  to  rock  may  be  loaded  to  the  above  limits. 
Piles  driven  through  loose,  wet  soil  to  solid  rock,  or  equivalent  bearing, 
shall  be  figured  as  columns  with  a  maximum  unit  stress  of  600  lb. 
per  sq.  in.,  properly  reduced. 

Masonry  Pillars  and  Walls  Laid  in  Cement  Mortar. 

Pillars.  20.  Pillars   of   brick   or   stone   masonry,    with   concentric   loading, 

may  be  built  of  a  height  not  exceeding  12  times  their  diameter  or 
their  least  lateral  dimension ;  providing  the  unit  pressure  comes  within 
the  limits  specified  for  the  different  classes  of  masonry. 

21.  The  dimensions  of  pillars  loaded  eccentrically  must  be  such 
that  the  center  of  pressure  comes  within  the  middle  third  of  the  base 
and  every  other  horizontal  section,  and  that  the  maximum  unit  pres- 
sure does  not  exceed  the  safe  working  pressure. 

Wails.  22.  The  thickness  of  a  wall  depends  upon  the  quality  of  the  material 

used,  the  load  it  has  to  carry,  and  upon  its  unsupported  height  or 


11 


length.  The  minimum  thickness  of  a  wall  of  brick  or  ashlar  masonry 
shall  be  TV  of  its  least  unsupported  distance,  either  vertically  or  hori- 
zontally; and  that  of  walls  of  rubble  masonry,  £  of  that  distance. 

23.  The  minimum  thickness  of  brick  enclosure  walls  shall  be  12 
in.,  and  that  of  stone  walls,  18  in. 

24.  The  minimum  thickness  of  curtain  walls  in  the  steel  skeleton 
type  of  buildings  shall  be  12  in. 

25.  The  unsupported  height  of  a  wall  shall  be  taken  as  the  height 
of  one  story,  provided  it  is  properly  anchored  to  the  floor  construc- 
tion of  each  story.     The  unsupported  distance  horizontally  shall  be 
taken  as  the  distance  between  lateral  walls  which  are  properly  bonded 
to  it,  or  the  distance  between  buttresses  or  steel  columns. 

26.  In  a  wall  carrying  joists  or  beams,  the  load  may  be  consid- 
ered as  distributed,  if  the  distance  between  the  beams  is  not  more 
than  twice  the  thickness  of  the  wall.     If  a  wall  has  to  support  con- 
centrated loads,  such  as  are  produced  by  heavy  roof  trusses  or  floor 
girders,   it  must  be  reinforced  by  buttresses,   which   should  be  com- 
puted as  pillars. 

27.  In  the  case  of  buildings  several  stories  in  height,  the  mini- 
mum thickness  of  the  exterior  walls  supporting  floors  and  roof  may  be 
approximately  determined  by  the  following  empirical  formula,  which 
gives   results   agreeing  with   the  provisions   of   most   of   the   existing 
building  laws. 


28.  The  thickness  of  wall  in  inches  t  =  -r  + 

4 


TT 


TT 


„ 
6 


where  L  =  unsupported  length  in  feet,  which  should  not  be  assumed 
less  than  24  ft.,  and  H^  fT2,  JT3,  etc.,  the  heights  of  the  stories  in  feet, 
commencing  at  the  top. 

29.  The  above  rules  apply  to  walls  of  brick  and  ashlar  masonry 
for  dwellings,  hotels  and  office  buildings. 

30.  The  cellar  wall  shall  generally.be  4  in.  thicker  than  the  wall 
immediately  above  it,  to  a  depth  of  12  ft.  below  the  grade  line;  and  for 
every  additional  10  ft.,  or  part  thereof,  shall  be  increased  4  in.     Cellar 
and  foundation  walls  of  masonry  shall  be  4  in.  thicker  than  brick  walls. 

31.  If  any  horizontal  section  through  any  bearing  wall  shows  more 
than  30%  area  of  flues  or  openings,  such  wall  shall  be  increased  in 
thickness  1  in.  for  every  4%,  or  fraction  thereof,  by  which  the  total 
areas   of  flues   and   openings   exceed  30  per  cent. 


Exterior 
Walls. 


Curtain 
Walls. 


Bearing 
Walls. 


Cellar  and 

Foundation 

Walls. 


12 


Non-bearing 
Walls. 


Permissible 
Stresses. 


Tension. 

Compression. 

Bending. 


Shear. 


Bearing. 


Axial 
Compression. 


Provision  for 

Eccentric 

Loading. 

Expansion 
Rollers. 


Combined 
Stresses. 


32.  The  thickness  of  non-bearing  walls  may  be  4  in.  less  than  that 
of  bearing  walls,  provided  that  no  non-bearing  wall  is  less  than  12  in. 
thick. 

STEEL  SUPERSTRUCTURE. 

Unit  Stresses. 

33.  All  parts   of  the  structure  shall  be  proportioned  so  that  the 
sum  of  the  dead  and  live  loads,  together  with  the   impact,   if   any, 
shall  not  cause  the  stresses  to  exceed  the  following  amounts  in  pounds 
per  sq.  in. : 

34.  Tension,  net  section,  rolled  steel 16  000 

35.  Direct  compression,  rolled  steel  and  steel  castings 16  000 

36.  Bending,   on  extreme  fibers  of  rolled  shapes,  built  sec- 

tions, girders  and  steel  castings,  net  section 16  000 

On  extreme  fibers  of  pins 24  000 

37.  Shear,  on  rivets  and  pins 12  000 

On  bolts  and  field  rivets 10  000 

On  plate-girder  web  (gross  section) .  .10  000 

38.  Bearing  pressure,  on  pins  and  rivets 24  000 

On  bolts  and  field  rivets 20  000 

39.  Axial  compression  on  gross  section  of  columns. .  .16  000  —  70  -- 

with  a  maximum  of 14  000 

Where  I  =  effective  length*  of  member  in  inches; 

r  =  corresponding   radius    of   gyration   of   the   section,    in 
inches. 

40.  For  bracing  and  the  combined  stresses  due  to  wind  and  other 
loading,  the  permissible  working  stresses  may  be  increased  25%,   or 
to  20,000  Ib.  for  direct  compression  or  tension. 

41.  In   proportioning    columns,    provision   must   be   made   for   ec- 
centric loading. 

42.  The  pressure  per  linear   inch   on   expansion   rollers   shall   not 
exceed  600  d,  where  d  —  diameter  of  rollers,  in  inches. 

43.  Members    subject    to    the    action    of    both    axial    and   bending 
stresses  shall  be  proportioned  so  that  the  greatest  fiber  stress  will  not 
exceed  the  allowed  limits  in  that  member. 

*  The  effective  length  "  I ",  if  L  is  the  length  of  the  member  between  centres  of  con- 
nections, shall  be  t&ken  as  follows  : 

I  =  L,  if  both  ends  are  hinged  or  butting  ; 

I  =  14  L,  if  both  ends  are  fixed  ; 

I  =  %  L,  if  one  end  is  fixed,  the  other  hinged  ; 

I  =  2  L,  if  one  end  is  fixed,  the  other  free  to  move. 


13 


44.  Members    subject    to    alternate    stresses    of   tension    and    com- 
pression shall  be  proportioned  for  the  stress  giving  the  largest  sec- 
tion, but  their  connections  shall  be  proportioned  for  the  sum  of  the 
stresses. 

45.  Net   sections   must   be   used   in   calculating   tension   members, 
and,   in  deducting  the  rivet  holes,  they  must  be  taken  J   in.  larger 
than  the  nominal  size  of  the  rivets. 

46.  Pin-connected  riveted  tension  members  shall  have  a  net  sec- 
tion through  the  pin  holes  25%  in  excess  of  the  net  section  of  the 
body  of  the  member.     The  net  section  back  of  the  pin  hole  shall  be 
at  least  0.75  of  the  net  section  through  the  pin  hole. 

47.  The  effective  length  of  main  compression  members  shall  not 
exceed  125  times  their  least  radius  of  gyration,  and  those  for  wind 
and  lateral  bracing,  150  times, their  least  radius  of  gyration. 

48.  The   length   of  riveted  tension  members   in  horizontal   or  in- 
clined positions  shall  not  exceed  200  times  their  radius  of  gyration 
about  the  horizontal  axis.     The  horizontal  projection  of  the  unsup- 
ported portion  of  the  member  is  to  be  considered  as  the  effective  length. 

49.  Plate   girders    shall   be   proportioned   on   the   assumption   that 
one-eighth  of  the  gross  area  of  the  web  is  available  as  flange  area. 
The  thickness  of  the  web  plate  shall  not  be  less  than  T£D  of  the  unsup- 
ported distance  between  flange  angles. 

50.  The  compression  flange  shall  have  at  least  the  same  sectional 
area  as  the  tension  flange;  nor  shall  the  strain  per  square  inch  on  the 

gross  area  exceed  16  000  —  200  p  if  cover  consists  of  flat  plates,  or 

16  000  —  150  -..  if  cover  consists  of  a  channel  section,  where  I  =  un- 
o 

supported  distance,  and  b  =  width  of  flange  in  inches. 

51.  The  web  shall  have  stiffeners  at  the  ends  and  inner  edges  of 
bearing  plates,   and  at  all  points  of  concentrated  loads,  and  also  at 
intermediate    points,    when    the   thickness    of   the    web    is    less    than 
one-sixtieth  of  the  unsupported  distance  between  flange  angles,  gen- 
erally not  farther  apart  than  the  depth  of  the  full  web  plate,  with  a 
maximum  limit  of  5  ft. 

52.  IE -beams,  and  channels  used  as  beams  or  girders,  shall  be  pro- 
portioned by  their  moments  of  inertia. 

53.  The  depth  of  rolled  beams  in  floors  shall  be  not  less  than  one- 
twentieth  of  the  span,  and,  if  used  as  roof  purlins,  not  less  than  one- 
thirtieth  of  the  span. 


Alternate 
Stresses. 


Net 
Sections. 


Limiting 
Length  of 
Members. 


Plate 
Girders. 


Compression 
Flanges  of 
Plate 
Girders. 


Web 

Stiffeners. 


Rolled 
Beams. 


Limiting 
Depth  of 
Beams  and 
Girders. 


14 


Permissible 
Stresses. 


Timber. 


Timber 
Columns. 


54.  In  case  of  floors  subject  •  to  shocks  and  vibrations,  the  depth 
of  beams  and  girders  shall  be  limited  to  one-fifteenth  of  the  span.     If 
shallower  beams  are  used,  the  sectional  area  shall  be  increased  until 
the  maximum  deflection  is  not  greater  than  thai?  of  a  beam  having  a 
depth  of  one-fifteenth  of  the  span,  but  the  depth  of  such  beams  and 
girders  shall  in  no  case  be  less  than  one-twentieth  of  the  span. 

Cast  Iron. 

55.  Compression    12  000  Ib.  per  sq.  in. 

Tension    2  500     "     "       "  " 

Shear    1  500     "     "       "  " 

Timber. 

56.  The   timber   parts   of   the   structure   shall   be  proportioned   in 
accordance  with   the  following  stresses,  given   in  pounds  per  square 
inch: 


Kind  of  timber. 

Transverse 
loadipg. 

End 
bearing. 

Columns 
under  10 
diameters. 

Bearing 
across 
fiber. 

Shear 
along  fiber. 

White  Oak  

1  200 

1  200 

1  000 

500 

200 

Long-Leaf  Yellow  Pine  

1  500 

1  500 

1  000 

350 

100 

White  Pine  and  Spruce  
Hemlock 

1  000 
800 

1  000 

800 

600 
500 

200 
200 

100 
100 

57.  Columns  may  be  used  with  a  length  not  exceeding  45  times 
the  least  dimension.  The  unit  stress  for  lengths  of 'more  than  10 
times  the  least  dimension  shall  be  reduced  by  the  following  formula : 


Planking. 


Minimum 
Thickness  of 
Material. 

Adjustable 
Members. 


Symmetrical 
Sections. 


100   d 

Where  G  equals  unit  stresses,  as  given  above  for  short  columns ; 
I        "     length  of  column,  in  inches; 
d        "      least  side  of  column,  in  inches. 

58.  For  the  thickness  of  floor  and  roof  planking,  see  Table  6. 

DETAILS  OF  STEEL  CONSTRUCTION. 

59.  No  steel  of  less  than  i  in.  thickness  shall  be  used,  except  for 
lining  or  filling  vacant  spaces. 

60.  Adjustable  members  in  any  part  of  structures  shall  preferably 
be  avoided. 

61.  Sections  shall  preferably  be  made  symmetrical. 


15 


Beam 
Girder. 


Wall  Ends 
of  Beams  and 
Girders. 

Wall-Plates 
and  Column 


62.  The  strength  of  connections  shall  be  sufficient  to  develop  the    Connections, 
full  strength  of  the  member. 

63.  No   connection,   except  lattice  bars,   shall  have  less  than  two 
rivets. 

64.  Floor  beams  shall  generally  be  rolled-steel  beams.  Floor  Beams. 

65.  For  fire-proof  floors,  they  shall  generally  be  tied  with  tie-rods 
at  intervals  not  exceeding  eight  times  the  depth  of  the  beams.     This 
spacing  may  be  increased  for  floors  which  are  not  of  the  arch  type 
of   construction.     Holes   for  tie-rods,  where  the  construction   of  the 
floor  permits,  shall  be  spaced  about  3  in.  above  the  bottom  of  the  beam. 

66.  When  more  than  one  rolled  beam  is  used  to  form  a  girder, 
they  shall  be  connected  by  bolts  and  separators  at  intervals  of  not 
more  than  5  ft.     All  beams  having  a  depth  of  12  in.  and  more  shall 
have  at  least  two  bolts  to  each  separator. 

67.  Wall  ends  of  a  sufficient  number  of  joists  and  girders  shall  be 
anchored  securely  to  impart  rigidity  to  the  structure. 

68.  Wall-plates  and  column  bases  shall  be  constructed  so  that  the 
load  will  be  well  distributed  over  the  entire  bearing.     If  they  do  not 
get  the   full  bearing  on  the  masonry,   the   deficiency  shall  be  made 
good  with  Portland-cement  mortar. 

69.  The  floor  girders  may  be  rolled  beams  or  plate  girders;  they 
shall  preferably  be  riveted  or  bolted  to  columns  by  means  of  connection 
angles.    Shelf  angles  or  other  supports  may  be  provided  for  convenience 
during  erection. 

70.  The  flange  plates  of  all  girders  shall  be  limited  in  width,  so  as 
not  to  extend  beyond  the  outer  line  of  rivets  connecting  them  to  the 
angles  more  than  6  in.,  or  more  than  eight  times  the  thickness  of  the 
thinnest  plate. 

71.  Web  stiffeners  shall  be  in  pairs,  and  shall  have  a  close  bearing 
against  the  flange  angles.     Those  over  the  end  bearing,  or  forming  the 
connection  between  girder  and  column,  shall  be  on  fillers.    Intermediate 
stiffeners  may  be  on  fillers  or  crimped  over  the  flange  angles.     The 
rivet  pitch  in  stiffeners  shall  not  be  more  than  5  in. 

72.  Web  plates  of  girders  must  be  spliced  at  all  points  by  a  plate    web  Splices, 
on  each  side  of  the  web,  capable  of  transmitting  the  full  stress  through 

splice  rivets. 

73.  Columns  shall  be  designed  so  as  to  provide  for  effective  con-     Columns, 
nections  of  floor  beams,  girders  or  brackets. 

They  shall  preferably  be  continuous  over  several  stories. 


Floor 
Girders. 


Flange 
Plates. 


Web 

Stiffeners. 


16 


Column 
Splices. 


Trusses. 


Intersecting 
Members. 


Roof  Trusses. 


Eye-Bars. 


Spacing  of 
Rivets. 


Edge 
Distance. 


Maximum 
Diameter. 


74.  The  splices  shall  be  strong  enough  to  resist  the  bending  stress 
and  make  the  columns  practically  continuous  for  their  whole  length. 

75.  Trusses  shall  preferably  be  riveted  structures.     Heavy  trusses, 
of  long  span,  where  the  riveted  field  connections  would  become  un- 
wieldy, or  for  other  good  reasons,  may  be  designed  as  pin-connected 
structures. 

76.  Main  members  of  trusses  shall  be  designed  so  that  the  neutral 
axes  of  intersecting  members  shall  meet  in  a  common  point. 

77.  Roof  trusses  shall  be  braced  in  pairs  in  the  plane  oi  the  chords. 
Purlins   shall   be   made   of   rolled   shapes,   plate  girders   or   lattice 

girders. 

78.  The   eye-bars   in   pin-connected    trusses    composing   a   member 
shall  be  as  nearly  parallel  to  the  axis  of  the  truss  as  possible. 

79.  The  minimum  distance  between  centers  of  rivet  holes  shall  be 
three   diameters    of   the   rivet;    but   the   distance    shall   preferably   be 
not  less  than  3  in.  for  |-in.  rivets,  2£  in.  for  f-in.  rivets,  and  If  in. 
for  £-in.   rivets.     The  maximum  pitch  in  the  line  of  the  stress  for 
members  composed  of  plates  and  shapes  shall  be  6  in.  for  |-in.  rivets, 
5  in.  for  f-in.  rivets,  4£  in.  for  |-in.  rivets  and  4  in.  for  ^-in.  rivets. 

80.  For  angles  with   two   gauge   lines,   with   rivets   staggered,   the 
maximum  in  each  line  shall  be  twice  as  great  as  given  in  Paragraph 
79;  and,  where  two  or  more  plates  are  used  in  contact,  rivets  not  more 
than  12  in.  apart  in  either  direction  shall  be  used  to  hold  the  plates 
together. 

81.  The  pitch  of  the  rivet,  in  the  direction  of  the  stress,  shall  not 
exceed  6  in.,  nor  16  times  the  thinnest  outside  plate  connected,  and 
not  more  than  50  times  that  thickness  at  right  angles  to  the  stress. 

82.  The  minimum  distance  from  the  center  of  any  rivet  hole  to  a 
sheared  edge  shall  be  1£  in.  for  £-in.  rivets,  1£  in.  for  f-in.   rivets, 
1|  in.  for  |-in.  rivets,  and  1  in.  for  £-in.  rivets;  and  to  a  rolled  edge, 
1£,  1|,  1  and  |  in.,  respectively. 

83.  The   maximum   distance   from   any   edge  shall  be   eight  times 
the  thickness  of  the  plate. 

84.  The  diameter  of  the  rivets  in  any  angle  carrying  calculated 
stresses  shall  not  exceed  one-quarter  of  the  width  of  the  leg  in  which 
they   are   driven.     In   minor   parts,   rivets   may   be   £    in.   greater   in 
diameter. 


IT 


Tie- 
Plates. 


85.  The  pitch  of  rivets  at  the  ends  of  built  compression  members    Pitch  at 

Ends. 

shall  not  exceed  four  diameters  of  the  rivets  for  a  length  equal  to  one 
and  one-half  times  the  maximum  width  of  the  member. 

86.  The  open  sides  of  compression  members  shall  be  provided  with 
lattice,  having  tie-plates  at  each  end  and  at  intermediate  points  where 
the  lattice  is  interrupted.     The  tie-plates  shall  be  as  near  the  ends 
as  practicable.     In  main   members,   carrying   calculated  stresses,   the 
end  tie-plates  shall  have  a  length  not  less  than  the  distance  between 
the  lines  of  rivets  connecting  them  to  the  flanges,  and  intermediate 
ones  not  less  than  half  this  distance. 

Their   thickness   shall   be   not   less   than   one-fiftieth   of   the   same 
distance. 

87.  The   latticing   of   compression   members   shall  be   proportioned    Lattice, 
to  resist  the  shearing  .stresses  corresponding  to  the  allowance  for  flex- 
ure provided  in  the  column  formula  in  Paragraph  39  by  the  term  70  —  • 

The  minimum  thickness  of  lattice  bars  shall  be  one-fortieth  for  single 
lattice  and  one-sixtieth  for  double  lattice,  of  the  distance  between  end 
rivets;  their  minimum  width  shall  be  as  follows: 


For  15-in.  channels,  or  built  sections  with  3£ 
and  4-in.  angles 

For  12,  10  and  9-in.  channels,  or  built  sections 
with  3-in.  angles 


j-  2£  in.  (I-in.  rivets)  ; 

i  2£  in.  (f -in  rivets)  ; 

For    8    and    7-in.    channels,    or    built    sections  )    n    .      ,...'..       •     .  \ 

>-  2    in.  (| -in.  rivets)  ; 
with  2^-in.  angles ' 

For  6  and  5-in.  channels,  or  built  sections  with)  „  „  .       ,,  .        •     .  \ 

j  If  in.  G-m.  rivets). 
2-in.  angles ) 

88.  Lattice  bars  with  two  rivets  shall  generally  be  used  in  flanges 
more  than  5  in.  wide. 

89.  The  inclination  of  lattice  bars  with  the  axis  of  the  member,    Angle  of 
shall  generally  be  not  less  than  45°,  and  when  the  distance  between 

the  rivet  lines  in  the  flange  is  more  than  15  in.,  if  a  single  rivet  bar 
is  used,  the  lattice  shall  be  double  and  riveted  at  the  intersection. 

90.  The  pitch  of  lattice  connections,  along  the  flange,  divided  by     Spacing  of 
the  least  radius  of  gyration  of  the  member  between  connections,  shall 

be  less  than  the  corresponding  ratio  of  the  member  as  a  whole. 


18 

Faced  91.  Abutting  joints  in  compression  members  when  faced  for  bearing 

shall  be  spliced  sufficiently  to  hold  the  connecting  members  accurately 
in  place. 

92.  All  other  joints  in  riveted  work,  whether  in  tension  or  com- 
pression, shall  be  fully  spliced. 

Pin  Plates.  93.  Pin  holes  shall  be  reinforced  by  plates  where  necessary ;  and  at 

least  one  plate  shall  be  as  wide  as  the  flange  will  allow;  where  angles 
are  used,  this  plate  shall  be  on  the  same  side  as  the  angles.  The  plates 
shall  contain  sufficient  rivets  to  distribute  their  portion  of  the  pin 
pressure  to  the  full  cross-section  of  the  member. 

Pins.  94.  Pins  shall  be  long  enough  to  insure  a  full  bearing  of  all  parts 

connected  upon  the  turned-down  body  of  the  pin. 

95.  Members  packed  on  pins  shall  be  held  against  lateral  movement. 

Bolts.  96.  Where  members  are  connected  by  bolts,  the  body  of  these  bolts 

shall  be  long  enough  to  extend  through  the  metal.  A  washer  at  least 
T3F  in.  thick  shall  be  used  under  the  nut. 

Fillers.  97.  Fillers   between   parts    carrying   stress    shall   have   a   sufficient 

number  of  independent  rivets  to  transmit  the  stress  to  the  member  to 
which  the  filler  is  attached. 

Temperature.         98.  Provision   shall  be  made  for  expansion   and  contraction,   cor- 
responding to  a  variation  of  temperature  of  150°  Fahr.  where  necessary. 

Rollers.  99.  Expansion  rollers  shall  be  not  less  than  4  in.  in  diameter. 

stone  Bolts.  100.  Stone  bolts  shall  extend  not  less  than  4  in.  into  granite  pedes- 

tals and  8  in.  into  other  material. 

Anchorage.  101.  Columns  which  are  strained  in  tension  at  their  base  shall  be 

anchored  to  the  foundations. 

102.  Anchor  bolts  shall  be  long  enough  to  engage  a  mass  of 
masonry,  the  weight  of  which  shall  be  one  and  one-half  times  the  ten- 
sion in  the  anchor. 

Bracing.  103.  Lateral,  longitudinal  and  transverse  bracing  in  all  structure? 

shall  preferably  be  composed  of  rigid  members. 

MATERIAL    AND    WORKMANSHIP. 
MATERIAL. 

steel.  104.  All  parts   of   the  metallic   structure  shall   be  of  rolled   steel, 

except  column  bases,  bearing  plates  or  minor  details,  which  may  be  of 
cast  iron  or  cast  steel. 


19 


105.  Steel  may  be  made  by  the  open-hearth   or  by  the  Bessemer     Process  of 

Manufacture. 

process. 

106.  The   chemical   and  physical  properties    shall   conform  to   the    Requirements, 
following  limits : 


Chemical  and  physical  properties. 

Structural 
steel. 

Rivet  steel. 

Steel 
castings. 

Phosphorus,  maximum  

0.040/0 

0.050/0 

0.04% 
0.04% 

0.05% 
0.059/0 

Sulphur,  maximum  

Ultimate    tensile  strength;  pounds  per 
square  'inch 

Desired 

60  000 
1  500  000* 

Desired 

50  000 
1  500  000 

Not  less  than 
65  000 

Elongation:  minimum  percentage  in  8J 
in                                                                 i 

Ultimate  tensile 
strength. 
M 

Silky. 
180°  flat.t 

Ultimate  tensile 
strength. 

( 
Elongation:  minimum  percentage  in  2  in. 
Character  of  fracture  

18 
Silky  or  fine 
granular. 
90° 

Silky.          -j 
180°  flat.§ 

Cold  bends  without  fracture 

*  See  Paragraph  117.    t  See  Paragraphs  118, 119  and  120.    §  See  Paragraph  121. 

107.  In   order   that   the    ultimate   strength    of   full-sized    annealed 
eye-bars  may  meet  the  requirements  of  Paragraph  170,  the  ultimate 
strength  in  test  specimens  may  be  determined  by  the  manufacturers ; 
all  other  tests  than  those  for  ultimate  strength  shall  conform  to  the 
above  requirements. 

108.  The  yield  point,  as  indicated  by-  the  drop  of  beam,  shall  be 
recorded  in  the  test  reports. 

109.  Tensile   tests   of  steel   showing   an   ultimate   strength   within 
5,000  Ib.  of  that  desired  will  be  considered  satisfactory. 

110.  Chemical  determinations  of  the  percentages  of  carbon,  phos- 
phorus, sulphur  and  manganese  shall  be  made  by  the  manufacturer 
from  a  test  ingot  taken  at  the  time  of  the  pouring  of  each  melt  of 
steel,  and  a  correct  copy  of  such  analysis  shall  be  furnished  to  the 
engineer  or  his  inspector. 

111.  Specimens  for  tensile  and  bending  tests  for  plates,  shapes  and 
bars  shall  be  made  by  cutting  coupons  from  the  finished  product,  which 
shall  have  both  faces  rolled  and  both  edges  milled  to  the  form  shown 
by  Fig.  1;  or  with  both  edges  parallel;  or  they  may  be  turned  to  a 
diameter  of  f  in.  for  a  length  of  at  least  9  in.,  with  enlarged  ends. 

112.  Rivet  rods  shall  be  tested  as  rolled. 

113.  Specimens  shall  be  cut  from  the  finished  rolled  or  forged  bar, 
in  such  manner  that  the  center  of  the  specimen  shall  be  1  in.  from 
the  surface  of  the  bar.      The  specimen  for  the  tensile  test  shall  be 


Allowable 
Variations. 


Chemical 
Analyses. 


Form  of 
Specimens 
for  Plates, 
Shapes  and 
Bars. 


Rivets. 


Pins  and 
Rollers. 


turned  to  the  form  shown  by  Fig.  2.     The  specimen  for  the  bending 
test  shall  be.l  in.  by  %  in.  in  section. 


Steel 
Castings. 


Specimens  of 
Rolled  Steel. 


Number  of 
Tests. 


Modifications 
in  Elonga- 
tion. 


Bending 
Tests. 


Thick 
Material. 


Bending 
Angles. 


/ 

About  3"   •£?  JParallei  Section 

;,«$>  j  "    Not  less  than  9"       j 


1 

v  j                    IK"  ! 

j,  ,  ?.  .•§!••: 

^^i^i^Etc. 

fc 

FIG.  l. 

FIG.  2. 


114.  The  number  of  tests  will  depend  on  the  character   and  im- 
portance of  the  castings.     Specimens  shall  be  cut  cold  from  coupons 
moulded  and  cast  on  some  portion  of  one  or  more  castings  from  each 
melt,  or  from  the  sink-heads,  if  the  heads  are  of  sufficient  size.     The 
coupon  or  sink-head,  so  used,  shall  be  annealed  with  the  casting  before 
it  is  cut  off.    Test  specimens  shall  be  of  the  form  prescribed  for  pins 
and  rollers. 

115.  Rolled  steel  shall  be  tested  in  the  condition  in  which  it  comes 
from  the  rolls. 

116.  At  least  one  tensile  and  one  bending  test  shall  be  made  from 
each  melt  of  steel  as  rolled.    In  case  steel  differing  §  in.  and  more  in 
thickness   is   rolled  from   one  melt,    a   test  shall   be   made   from   the 
thickest  and  thinnest  material  rolled. 

117.  For  material  more  than  f  in.  in  thickness, 'a  deduction  of  1% 
will  be  allowed  from  the  specified  elongation  for  each  J  in.  in  thickness 
above  |  in. 

118.  Bending  tests  may  be  made  by  pressure  or  by  blows.     Plates, 
shapes  and  bars  less  than  1  in.  thick  shall  bend  as  called  for  in  Para- 
graph 106. 

119.  Full-sized  material  for  eye-bars  and  other  steel  1  in.  or  more 
in  thickness,  tested  or  rolled,  shall  bend  cold  180°  around  a  pin,  the 
diameter  of  which  is  equal  to  twice  the  thickness  of  the  bar,  without 
fracture  on  the  outside  of  the  bend. 

120.  Angles  f  in.  and  less  in  thickness  shall  open  flat,  and  angles  \ 
in.  and  less  in  thickness  shall  bend  shut,  cold,  under  blows  of  a  ham- 


21 


Nicked 
Bends. 


Defective 
Material. 


mer,  without  sign  of  fracture.  This  test  will  be  made  only  when  re- 
quired by  the  inspector. 

121.  Kivet  steel,  when  nicked  and  bent  around  a  bar  of  the  same 
diameter  as  the  rivet  rod,  shall  give  a  gradual  break  and  a  fine,  silky, 
uniform  fracture. 

122.  Finished  material  shall  be  free  from  injurious  seams,  flaws,    Finish, 
oracks,   defective  edges,   or  other  defects,   and  shall  have   a  smooth, 
uniform,  workmanlike  finish.     Plates  36  in.   and  less  in  width  shall 

have  rolled  edges. 

123.  Every  finished  piece  of  steel  shall  have  the  melt  number  and    stamping 
the  name  of  the  manufacturer  stamped  or  rolled  upon  it.     Steel  for 

pins  and  rollers  shall  be  stamped  on  the  end.  Rivet  and  lattice  steel 
and  other  small  parts  may  be  bundled  with  the  above  marks  on  an  at- 
tached tag. 

124.  Material  which,  subsequent  to  the  foregoing  tests  at  the  mills, 
and  its  acceptance  there,  develops  weak  spots,  brittleness,  cracks  or 
other  imperfections,  or  is  found  to  have  injurious  defects,  will  be  re- 
jected at  the  shop,  and  shall  be  replaced  by  the  manufacturer  at  his  own 
cost. 

125.  A  variation  in  cross-section  or  weight  in  the  finished  members 
of  more  than  2£%  from  that  specified  "will  be  sufficient  cause  for  re- 
jection. 

126.  Iron  castings  shall  be  made  of  tough,  gray  iron,  free  from  in-    cast  iron, 
jurious  cold-shuts  or  blow-holes,  true  to  pattern  and  of  workmanlike 

finish.  Test  pieces  1|  in.  round  shall  be  capable  of  sustaining  on  a  clear 
span  of  12  in.  a  central  load  of  at  least  2  900  lb.,  and  deflect  at  least 
TO-  in.  before  rupture. 

WORKMANSHIP. 

127.  All  parts  forming  a  structure  shall  be  built  in  accordance  with    General, 
approved  drawings.    The  workmanship  and  finish  shall  be  equal  to  the 

best  practice  in  modern  bridge  works. 

128.  Material   shall    be   thoroughly   straightened   in    the   shop,   by 
methods  which  will  not  injure  it,  before  being  laid  off  or  worked  in  any 
way. 

129.  Shearing  shall  be  done  neatly  and  accurately,  and  all  portions    Finish, 
of  the  work  exposed  to  view  shall  be  neatly  finished. 

130.  The  size  of  rivets  called  for  on  the  plans  shall  be  understood  to    Rivets, 
mean  the  actual  size  of  the  cold  rivet  before  heating. 


Allowable 
Variation 
in  Weight. 


Straightening 
Material. 


Rivet 
Holes. 


Punching. 


Assembling. 


Lattice  Bars. 


Web 
Stiffeners. 


Splice  Plates 
and  Fillers. 


Connection 
Angles. 


Riveting. 


Heating  of 
Rivets. 


Rivets. 


Field  Bolts. 


Members  to 
be  Straight. 


131.  The  diameter  of  the  punch  for  material  not  more  than  f  in. 
thick  shall  be  not  more  than  TV  in.,  nor  that  of  the  die  more  than  | 
in.  larger  than  the  diameter  of  the  rivet.   Material  more  than  f  in.  thick, 
excepting  in  minor  details,  shall  be  sub-punched  and  reamed  or  drilled 
from  the  solid. 

132.  Punching  shall  be  done  accurately.     Slight  inaccuracy  in  the 
matching  of  holes  may  be  corrected  with  reamers.    Drifting  to  enlarge 
unfair  holes   will   not  be  allowed.      Poor  matching  of  holes   will  be 
cause  for  rejection,  at  the  option  of  the  inspector. 

133.  Riveted   members   shall  have   all   parts   well  pinned   up    and 
firmly  drawn  together  with  bolts  before  riveting  is  commenced.     Con- 
tact surfaces  shall  be  painted.     (See  Paragraph  157.) 

134.  Lattice  bars  shall  have  neatly  rounded  ends,  unless  otherwise 
called  for. 

135.  Stiffeners  shall  fit  neatly  between  the  flanges  of  girders.   Where 
tight  fits  are  called  for,  the  ends  of  the  Stiffeners  shall  be  faced  and 
shall  be  brought  to  a  true  contact  bearing  with  the  flange  angles. 

136.  Web  splice  plates  and  fillers  under  Stiffeners  shall  be  cut  to 
fit  within  i  in.  of  flange  angles. 

137.  Connection  angles  for  floor  girders  shall  be  flush  with  each 
other  and  correct  as  to  position  and  length  of  girder. 

138.  Rivets   shall   be   driven   by   pressure   tools   wherever  possible. 
Pneumatic  hammers  shall  be  used  in  preference  to  hand  driving. 

139.  Rivets  shall  be  heated  to  a  light  cherry-red  heat  in  a  gas  or 
oil  furnace.   The  furnace  must  be  so  constructed  that  it  can  be  adjusted 
to  the  proper  temperature. 

140.  Rivets  shall  look  neat  and  finished,  with  heads  of  approved 
shape,  full,  and  of  equal  size.    They  shall  be  central  on  the  shank  and 
shall  grip  the  assembled  pieces  firmly.     Recupping  and  caulking  will 
not  be  allowed.   Loose,  burned,  or  otherwise  defective  rivets  shall  be  cut 
out  and  replaced.     In  cutting  out  rivets,  great  care  shall  be  taken 
not  to  injure  the  adjoining  metal.     If  necessary,  they  shall  be  drilled 
out. 

141.  Wherever  bolts   are   used  in  place   of   rivets   which   transmit 
shear,  such  bolts  must  have  a  driving  fit.    A  washer  not  less  than  £  in. 
thick  shall  be  used  under  the  nut. 

142.  The  several  pieces  forming  one  built  member  shall  be  straight 
and  shall  fit  closely  together,  and  finished  members  shall  be  free  from 
twists,  bends  or  open  joints. 


23 


143.  Abutting  joints  shall  be  cut  or  dressed  true  and  straight  and 
fitted  closely  together,  especially  where  open  to  view.    In  compression 
joints  depending  on  contact  bearing,  the  surfaces  shall  be  truly  faced, 
so  as  to  have  even  bearings  after  they  are  riveted  up  complete  and 
when  perfectly  aligned. 

144.  Eye-bars  .shall  be  straight  and  true  to  size,  and  shall  be  free 
from  twists,  folds  in  the  neck  or  head,  or  any  other  defect.    Heads  shall 
be  made  by  upsetting,  rolling  or  forging.    Welding  will  not  be  allowed. 
The  form  of  the  heads  will  be  determined  by  the  dies  in  use  at  the 
works  where  the  eye-bars  are  made,  if  satisfactory  to  the  engineer, 
but  the  manufacturer  shall  guarantee  the  bars  to  break  in  the  body 
when  tested  to  rupture.     The  thickness  of  the  head  and  neck  shall  not 
vary  more  than  ^  in.  from  that  specified. 

145.  Before  boring,  each  eye-bar  shall  be  perfectly  annealed  and 
carefully  straightened.    Pin  holes  shall  be  in  the  center  line  of  bars  and 
in  the  center  of  heads.     Bars  of  the  same  length  shall  be  bored  so 
accurately  that,  when  placed  together,  pins  -^  in.  smaller  in  diameter 
than  the  pin  holes  can  be  passed  through  the  holes  at  both  ends  of 
the  bars  at  the  same  time. 

146.  Pin  holes  shall  be  bored  true  to  gauges,  smooth  and  straight;  at 
right  angles  to  the  axis  of  the  member,  and  parallel  to  each  other,  un- 
less otherwise  called  for.    Wherever  possible,  the  boring  shall  be  done 
•after  the  member  is  riveted  up. 

147.  The  distance  from  center  to  center  of  pin  holes  shall  be  cor- 
rect within  -fa  in.,  and  the  diameter  of  the  hole  not  more  than  ^o  in. 
larger  than  that  of  the  pin,  for  pins  up  to  5  in.  diameter,  and  ^  in. 
for  larger  pins. 

148.  Pins  and  rollers  shall  be  turned  accurately  to  gauges,  and  shall 
be  straight,  smooth  and  entirely  free  from  flaws. 

149.  At  least  one  pilot  and  driving  nut  shall  be  furnished  for  each 
size  of  pin  for  each  structure. 

150.  Screw  threads  shall  make  tight  fits  in  the  nuts,  and  shall  be 
United  States  standard,  except  for  diameters  greater  than  If  in.,  when 
they  shall  be  made  with  six  threads  per  inch. 

151.  Steel,  except  in  minor  details,  which  has  been  partially  heated 
shall  be  properly  annealed. 

152.  All  steel  castings  shall  be  annealed. 

153.  Welds  in  steel  will  not  be  allowed. 


Finish  of 
Joints. 


Eye- Bars. 


Boring 
Eye-Bars. 


Pin  Holes. 


Variation  in 
Pin  Holes. 


Pins  and 
Rollers. 


Pilot  Nuts. 


Screw 
Threads. 


Annealing. 


Steel 
Castings. 

Welds. 


24 


Bed-Plates. 


Shipping 
Details. 


Shop 
Painting. 


Field 
Painting. 


Facilities  for 
Inspection. 


Access  to 
Shop. 


Mill  Orders. 


154.  Expansion  bed-plates  shall  be  planed  true  and  smooth.     Cast 
wall-plates  shall  be  planed  at  top  and  bottom.    The  cut  of  the  planing 
tool  shall  correspond  with  the  direction  of  expansion. 

155.  Pins,  nuts,  bolts,  rivets  and  other  small  details  shall  be  boxed 
or  crated. 

PAINTING. 

156.  Steelwork,  before  leaving  the  shop,  shall  be  thoroughly  cleaned 
and  given  one  good  coating  of  pure  linseed  oil,  or  such  paint  as  may 
be  called  for,  well  worked  into  all  joints  and  open  spaces. 

157.  In   riveted   work,    the   surfaces    coming    in    contact    shall    be 
painted  before  being  riveted  together. 

158.  Pieces  and  parts  which  are  not  accessible  for  painting  after 
erection  shall  have  two  coats  of  paint  before  leaving  the  shop. 

159.  Steelwork  to  be  entirely  embedded  in   concrete   shall  not  be 
painted. 

160.  Painting  shall  be  done  only  when  the  surface  of  the  metal 
is  perfectly  dry.    It  shall  not  be  done  in  wet  or  freezing  weather,  unless 
protected  under  cover. 

161.  Machine-finished    surfaces    shall    be    coated    with,  white    lead 
and  tallow  before  shipment,  or  before  being  put  out  into  the  open  air. 

162.  After  the  structure  is  erected,  the  metal-work  shall  be  painted 
thoroughly  and  evenly  with  an  additional  coat  of  paint,  mixed  with 
pure  linseed  oil,  of  such  quality  and  color  as  may  be  selected.     Suc- 
ceeding coats  of  paint  shall  vary  somewhat  in  color,  in  order  that 
there   may   be    no    confusion    as    to    the    surfaces    which   have    been 
painted. 

INSPECTION  AND  TESTING. 

163.  The  manufacturer  shall  furnish  all  facilities  for  inspecting  and 
testing  the  weight,  quality  of  material  and  workmanship.     He  shall 
furnish  a  suitable  testing  machine  for  testing  the  specimens,  as  well  as 
prepare  the  pieces  for  the  machine,  free  of  cost. 

164.  When  an  inspector  is  furnished  by  the  purchaser,  he  shall  have 
full  access  at  all  times  to  all  parts  of  the  works  where  material  under 
his  inspection  is  manufactured. 

165.  The   purchaser   shall   be   furnished    with    complete   copies    of 
mill  orders,  and  no  material  shall  be  rolled  and  no  work  done  before 
he  has  been  notified  as  to  where  the  orders  have  been  placed,  so  that 
he  may  arrange  for  the  inspection. 


25 


.T 
Invoices. 


166.  The   purchaser   shall   also   be   furnished   with   complete   shop    ghop  Plans, 
plans,  and  must  l^e  notified  well  in  advance  of  the  start  of  the  work  in 

the  shop,  in  ordei  that  he  may  have  an  inspector  on  hand  to  inspect 
the  material  and  workmanship. 

167.  Complete   copies   of   shipping   invoices   shall   be  furnished   to 
the  purchaser  with  each  shipment. 

168.  If  the  inspector,  through  an  oversight  or  otherwise,  has  ac-    Accepting 
cepted  material  or  work  which  is  defective  or  contrary  to  the  specifica-    or  Work, 
tions,  this  material,  no  matter  in  what  stage  of  completion,  may  be 
rejected  by  the  purchaser. 

FULL-SIZED  TESTS. 

169.  Full-sized   tests   on   eye-bars    and   similar   members,   to  prove 
the  workmanship,  shall  be  made  at  the  manufacturer's  expense,  and 
shall  be  paid  for  by  the  purchaser  at  contract  price,  if  the  tests  are 
satisfactory.     If     the     tests     are     not     satisfactory,     the     members 
represented  by  them  will  be  rejected. 

170.  In   eye-bar    tests,    the   minimum    ultimate    strength   shall    be 
55  000  Ib.  per  sq.  in.     The  elongation  in  10  ft.,  including  fracture,  shall 
be  not  less  than  15%.     Bars  shall  break  in  the  body  and  the  fracture 
shall  be  silky  or  fine  granular,  and  the  elastic  limit  as  indicated  by  the 
drop  of  the  mercury  shall  be  recorded.    Should  a  bar  break  in  the  head 
and  develop  the  specified  elongation,  ultimate  strength  and  character 
of  fracture,   it  shall  not  be   cause   for  rejection,  provided   not  more 
than  one-third  of  the  total  number  of  bars  break  in  the  head. 


27 

CONCRETE  AND  REINFORCED  CONCRETE. 
Concrete,  plain  and  reinforced,  may  now  be  considered  one  of  the 
recognized  materials  of  construction.     It  has  proved  to  be  satisfactory 
material,  when  properly  used,  for  those  purposes  for  which  its  quali- 
ties make  it  particularly  suitable. 

PROPER  USE. 

Concrete  is  a  material  of  very  low  tensile  strength  and  capable 
of  sustaining  but  very  small  tensile  deformations  without  rupture; 
its  value  as  a  structural  material  depends  chiefly  upon  its  durability, 
its  fire-resisting  qualities,  its  strength  in  compression  and  its  rela- 
tively low  cost.  Its  strength  generally  increases  with  age. 

Plain,  or  massive,  concrete  is  well  adapted  for  the  construction 
of  massive  structural  parts,  which  have  to  resist  compression  only, 
and  as  a  substitute  for  stone  or  brick  masonry  in  foundations,  walls, 
piers,  arches,  culverts,  docks,  dams,  reservoirs,  sewers,  tunnel  lin- 
ings, etc. 

For  such  purposes  concrete  has  stood  the  test  of  time,  and  may  be 
used  without  reinforcement  in  blocks,  or  as  a  monolith.  It  has  these 
advantages  over  stone  masonry,  that  material  for  the  aggregate  can  be 
found  in  almost  any  locality,  and  the  concrete  can  easily  be  put  in 
place,  under  proper  supervision,  without  skilled  workmen.  Concrete 
in  monolithic  form  is  better  adapted  to  receive  reinforcement  than 
stone  masonry. 

In  substructures  and  foundations,  the  bases  can  be  more  conveniently 
and  effectively  enlarged  by  reinforcing.  For  certain  kinds  of  ma- 
sonry construction  for  which  concrete  is  now  extensively  substituted, 
such  as  dams,  retaining  walls,  etc.,  engineers  have  been  able,  by  the 
use  of  proper  reinforcement,  to  depart  from  the  usual  forms  of  con- 
struction and  adopt  new  ones. 

Owing  to  its  fire-resisting  qualities,  reinforced  concrete  is  a  suit- 
able material  for  fire-proof  construction  for  floor  and  roof  slabs,  curtain 

walls,  partitions,  etc. 

IMPROPER  USE. 

Failures  of  reinforced  concrete  structures  are  usually  due  to  any 
one  or  a  combination  of  the  following  causes:  Defective  design,  poor 
material  and  faulty  execution. 

The  defects  in  a  design  may  be  many  and  various.  The  computa- 
tions and  assumptions  on  which  they  are  based  may  be  faulty  and 


28 

contrary  to  the  established  principles  of  statics;  the  unit  stresses  used 
may  be  excessive,  or  the  details  of  the  design  defective. 

As  the  properties  of  concrete  and  reinforced  concrete  are  not  yet 
as  well  understood  and  clearly  denned  as  those  of  steel,  owing  to  the 
lack  of  conclusive  tests  and  experience,  and  as  there  is  no  generally 
accepted  theory  in  existence  at  the  present  time  for  computing  the 
interior  forces  in  reinforced  concrete  structures,  the  data  which  are 
now  available  should  be  used  with  caution,  so  that  if  there  be  an  error, 
it  will  be  on  the  side  of  safety. 

The  design  of  a  structure  built  of  reinforced  concrete  should,  there- ' 
fore,  receive  at  least  the  same  careful  consideration  as  one  of  steel, 
and  only  engineers  with  sufficient  experience  and  good  judgment  should 
be  intrusted  with  such  work.     . 

The  computations  should  include  all  the  minor  details,  which  are 
sometimes  of  the  utmost  importance.  The  design  should  show  clearly 
the  size  and  position  of  the  reinforcement,  and  should  provide  for 
proper  connections  between  the  component  parts  so  that  they  cannot 
be  displaced.  The  best  results  are  obtained  when  the  reinforcement 
of  any  member  is  a  unit,  so  that  the  reinforcement  can  be  put  in 
position  without  depending  on  the  laborers  to  put  each  bar  in  its 
proper  place.  As  the  connections  between  the  members  are  generally 
the  weakest  points,  the  design'  should  provide  for  proper  attach- 
ments between  the  reinforcements  of  connecting  members  and  should 
be  accompanied  by  computations  to  prove  their  strength. 

The  use  of  unwarranted  high  unit  stresses,  approaching  the  danger 
line,  is  one  of  the  common  defects  in  the  design  of  reinforced  con- 
crete structures. 

Articulated  concrete  structures  designed  in  imitation  of  steel 
trusses  may  be  mentioned  as  illustrating  the  improper  use  of  rein- 
forced concrete.  Long  concrete  columns,  reinforced  with  longitudinal 
round  or  square  bars  intended  to  take  compression,  but  which  cannot 
resist  buckling,  may  also  be  mentioned  in  this  connection. 

Poor  material  is  sometimes  used  for  the  concrete,  as  well  as  for 
the  reinforcement.  Poor  concrete  is  not  always  used  intentionally, 
but  is  often  allowed  to  go  into  the  structure  owing  to  the  lack  of  ex- 
perience of  the  contractor  and  his  superintendents,  or  to  the  absence 
of  proper  supervision. 

A  poor  quality  of  steel  for  reinforcement  is  sometimes  called  for 
in  the  specifications  for  the  purpose  of  reducing  the  cost.  For  steel 


29 

structures,  a  high  grade  of  material  is  used,  while  the  steel  used  for 
reinforcing  concrete  is  sometimes  made  of  old  rails  or  other  unsuita- 
ble, brittle  material,  which  is  not  fit  to  be  used  in  any  permanent 
structure. 

Faulty  execution  and  careless  workmanship  may  generally  be  at- 
tributed to  unintelligent,  insufficient  supervision. 

The  remarks  referring  to  the  improper  uses  of  reinforced  con- 
crete apply  more  particularly  to  building  construction,  where  rational 
design,  good  material,  good  workmanship  and  adequate  supervision 
are  the  exception  rather  than  the  rule. 

While  other  structures  upon  the  safety  of  which  human  lives  de- 
pend are  generally  designed  by  engineers  employed  by  the  owner,  and 
the  contracts  let  on  the  engineer's  design  and  specifications,  in  accord- 
ance with  legitimate  practice,  reinforced  concrete  structures  are  as  a 
rule  designed  by  contractors  or  engineers  commercially  interested,  and 
the  contract  let  for  a  lump  sum,  without  the  advice  of  a  competent 
engineer,  and  regardless  of  the  merits  of  the  design. 

The  construction  of  buildings  in  large  cities  is  regulated  by  mu- 
nicipal authorities.  For  reinforced  concrete  work,  however,  the  lim- 
ited supervision  which  municipal  inspectors  are  able  to  give  is  not 
sufficient.  Other  means  for  more  adequate  supervision  and  inspection 
should,  therefore,  be  provided. 

RESPONSIBILITY  AND  SUPERVISION. 

If  any  failure  occurs  in  an  important  engineering  structure,  the 
engineer  is  generally  held  responsible  for  the  same.  In  recent  fail- 
ures of  reinforced  concrete  buildings,  coroners'  juries  either  put  the 
responsibility  on  unknown  causes,  or  on  some  ignorant,  innocent  sub- 
ordinate, who  had  to  act  as  scapegoat  for  his  employer. 

Disasters  have  proved  that  the  execution  of  the  work  should  not 
be  separated  from  the  designing  of  the  structure.  Intelligent,  ra- 
tional supervision  and  execution  of  the  work  can  be  expected  only  when 
both  functions  are  combined.  The  engineer  who  prepares  the  design 
and  specifications  should  also  have  the  supervision  of  the  execution 
of  the  work,  and  may  then  he  held  responsible  for  its  entire  construc- 
tion, unless  it  can  be  proven  that  the  contractor  has  done  work  con- 
trary to  design,  specifications  and  orders  of  the  engineer,  which  the 
engineer  and  his  inspectors  were  unable  to  prevent.  In  this  case  the 
contractor  should  be  held  responsible. 


30 

For  the  purpose  of  fixing  the  responsibility  and  providing  for 
adequate  supervision  during  construction,  the  Special  Committee  on 
Concrete  and  Reinforced  Concrete  of  the  American  Society  of  Civil 
Engineers  recommends  the  following  rules: 

a.  Before  work  is  commenced,  complete  plans  shall  be  pre- 
pared, accompanied  by  specifications,  static  computations  and  de- 
scriptions showing  the  general  arrangement  and  all  details.  The 
static  computations  shall  give  the  loads  assumed  separately,  such 
as  dead  and  live  loads,  wind  and  impact,  if  any,  and  the  result- 
ing stresses. 

Z>.  The  specifications  shall  state  the  qualities  of  the  materials 
to  be  used  for  making  the  concrete,  and  the  manner  in  which 
they  are  to  be  proportioned. 

c.  The  strength  which  the  concrete  is  expected  to  attain  after  a 
definite  period  shall  be  stated  in  the  specifications. 

d.  The  drawings  and  specifications  shall  be  signed  by  the  en- 
gineer and  the  contractor. 

e.  The  approval  of  plans  and  specifications  by  other  authorities 
shall  not  relieve  the  engineer  nor  the  contractor  of  responsibility. 


31 

SPECIFICATIONS    FOR   PLAIN   AND   REINFORCED 
CONCRETE  CONSTRUCTION. 

The  following  tentative  specifications  apply   to   all  structures,   or 
parts  thereof,  built  of  plain  or  reinforced  concrete: 

DESIGN. 

1.  In  the  design  of  massive  concrete  or  plain  concrete,  no  account    Massive 
should  be  taken  of  the  tensile  strength  of  the  material,  and  sections 
should  usually  be  so  proportioned  as  to  avoid  tensile  stresses.     This 

will  generally  be  accomplished,  in  the  case  of  rectangular  shapes,  if 
the  line  of  pressure  is  kept  within  the  middle  third  of  the  section, 
but  in  very  large  structures,  such  as  high  masonry  dams,  a  more  exact 
analysis  may  be  required.  Structures  of  massive  concrete  are  able 
to  resist  unbalanced  lateral  forces  by  reason  of  their  weight,  hence  the 
element  of  weight  rather  than  strength  often  determines  the  design. 
A  relatively  cheap  and  weak  concrete  will  therefore  often  be  suitable 
for  massive  concrete  structures.  Owing  to  its  low  extensibility,  the 
contraction  due  to  hardening  and  to  temperature  changes  requires  spe- 
cial consideration,  and,  except  in  the  case  of  very  massive  walls,  such 
as  dams,  it  is  desirable  to  provide  joints  at  intervals  to  localize  the 
effect  of  such  contraction.  The  spacing  of  such  joints  will  depend 
upon  the  form  and  dimensions  of  the  structure  and  its  degree  of 
exposure. 

2.  Massive  concrete  may  be  used  for  piers  and  short  columns  in 
which  the  ratio  of  length  to  least  width  is  relatively  small.     Under 
ordinary  conditions  this  ratio  should  not  exceed  six,  but,  where  the 
central  application  of  the  load  is  assured,  a  somewhat  higher  value 
may  safely  be  used. 

3.  Massive  concrete  is  also  a  suitable  material  for  arches  of  moderate 
span  where  the  conditions  as  to  foundations  are  favorable. 

4.  By  the  use  of  metal  reinforcement  to  resist  the  principal  tensile    Reinforced 
stresses,  concrete  becomes  available  for  general  use  in  a  great  variety 

of  structures  and  structural  forms.  This  combination  of  concrete  and 
steel  may  be  used  to  advantage  in  the  beam,  where  both  compression 
and  tension  exist;  and  the  column,  where  the  main  stresses  are  com- 
pressive,  but  where  cross-bending  may  exist.  The  theory  of  design 
will  therefore  relate  mainly  to  the  analysis  of  beams  and  columns. 


GENERAL  ASSUMPTIONS  FOR  STATIC  COMPUTATIONS. 
External  Forces. 

5.  Buildings  of  reinforced  concrete  are  to  be  designed  for  the  same 
vertical  loads  and  wind  pressure  as  specified  on  pages  7-9,  the  weight 
of  reinforced  concrete  to  be  assumed  at  150  Ib.  per  cu.  ft. 

6.  For  the  computations  of  the  end  reactions,  moments  and  shear, 
the  established  rules  of  statics  and  of  elasticity  shall  be  followed. 

7.  In  order  to  obtain  the  maximum  values,  the  most  unfavorable 
positions  and  distributions  of  the  live  load  must  be  considered. 

8.  Possible  effects  of  impact  may  be  considered  by  adding  the  usual 
percentage  to  the  live  load. 

9.  The  span  length  for  computations  is  to  be  taken  as  follows : 

a.  For  beams,  the  distance  between  centers  of  supports;  but 
shall  not  be  taken  to  exceed  the  clear  span  plus  the  depth  of  the 
beam. 

fc.  For  freely  supported  floor  slabs,  the  clear  span  plus  the 
thickness  of  the  slab  in  the  center. 

c.  For  continuous  slabs,  the  distance  center  to  center  of  beams. 

10.  For  continuous  beams  and  slabs,  the  bending  moment  at  center 
and  at  support  shall  be  taken  as  f  of  the  moment  of  a  freely  sup- 
ported beam  of  the  same  span. 

11.  For  square  floor  slabs  reinforced  in  both  directions   and  sup- 
ported on  all  sides,  the  bending  moment  may  be  taken  as  §  of  that 
of  a  freely  supported  beam  of  the  same  length. 

12.  In  computing  the  strength  of  columns,  the  possibility  of  ec- 
centric loading  must  be  considered. 

13.  In  the  design  of  T-beams  acting  as  continuous  beams,  due  con- 
sideration should  be  given  to  the  compressive  stresses  at  the  supports. 
For  beams  of  T-sections,  the  width  of  the  floor  slab  to  be  considered 
as  part  of  the  beam  shall  not  be  more  than  8  times  the  thickness  of 
the  slab,  or  J  of  the  span  length  of  the  beam. 

INTERNAL  STRESSES. 

14.  The  internal  stresses  in  reinforced  concrete  structures  shall  be 
determined  the  same  as  in  the  case  of  homogenous  material  on  the 
following  assumptions : 


33 


Moduli  of 
Elasticity. 


15.  (a)   The  stress  in  any  fiber  is  directly  proportionate  to  the  dis- 
tance of  that  fiber  from  the  neutral  axis. 

16.  (fc)   The  modulus   of   elasticity   of   the  concrete   remains   con- 
stant within  the  limits  of  the  working  stresses  fixed  in  these  specifica- 
tions.    In  compression,  the  two  materials   are,  therefore,  strained  in 
proportion  to  their  moduli  of  elasticity. 

17.  (c)  The  bond  between  the  concrete  and  steel  is  sufficient  to 
make  the  two  materials  act  together  as  a  homogeneous  solid. 

18.  The  ratio  of  the  modulus  of  elasticity  of  steel  to  the  modulus 
of  elasticity  of  stone  concrete  may  be  taken  at  15,  and  of  cinder  con- 
crete at  30. 

19.  The  tensile  strength  of  the  concrete  shall  be  neglected. 

20.  When  the  shearing  stresses  developed  in  any  part  of  the  constuc- 
tion  exceed  the  safe  working  strength  of  concrete  as  specified,  a  suffi- 
cient amount  of  reinforcement  shall  be  introduced  in  such  manner 
that  the  deficiency  in  the  resistance  to  shearing  is  overcome. 

21.  When  the  safe  limit  of  bond  between  the  concrete  and  the  steel 
is  exceeded,  some  provision  must  be  made  for  transmitting  the  strength 
of  the  steel  to  the  concrete. 

22.  For  columns  reinforced  with  shapes  that  can  resist  buckling, 
the  computations  may  be  made  in  the  same  manner  as  for  homoge- 
neous material,  if,  in  the  areas  and  moments  of  resistence,  the  sec- 
tion of  steel  reinforcement  is  added  to  that  of  the  concrete  with  15 
times  its  value. 

23.  In  columns  with  concentric  loading,  buckling  need  not  be  con- 
sidered if  the  ratio  of  the  effective  length  to  the  effective  diameter 
does    not   exceed    12.     The    effective    diameter   to   correspond   to    the 
assumed  theoretical  area. 

24.  If  tensile  stresses  produced  by  eccentric  loads  or  bending  mo- 
ments occur  in  a  column,  the  steel  reinforcement  on  the  tension  side 
must  be  able  to  resist  the  same. 

WORKING  STRESSES. 

25.  The   following   working   stresses    are   recommended    for    static 
loads : 


26.  For  the  steel  reinforcement,  the  unit  stresses  shall  not  exceed    steel, 
those  specified  for  other  structural  steel  work.      (Paragraph  33,  page  12.) 

27.  The  following  working  stresses  for  concrete  are  based  on  the    Concrete. 


Reinforced 
Columns. 


34 


Stone 
Concrete. 


compressive  strength  of  the  concrete,  developed  after  28  days,  when 
tested  in  cylinders  8  in.  in  diameter  and  16  in.  long: 


^Bearing 30%   of  the  compressive  strength. 

Compression  in  extreme  fiber 25% 

Axial  compression  in  columns. .. .  .20% 

Shear 3% 

Bond,  rolled  bars 3% 


a  a 

«  a 

a  « 

a  a 


28.  For  stone  concrete  composed  of  one  part  Portland  cement  and  6 
parts  aggregate,  capable  of  developing  an  average  compressive  strength 
of  2  000  Ib.  per  sq.  in.,  at  28  days,  the  working  stresses  shall  not  exceed 
the  following: 

Bearing    600  Ib.  per  sq.  in. 

Compression  in  extreme  fiber,  r 500    "       " 

Axial   compression   in   columns 400    "       "         " 

Shear 60    "       "         " 

Bond,    rolled    bars 60   "       "         " 

"        drawn   wire 40"       "         " 

29.  For   cinder   concrete   capable   of   developing   an    average   com- 
pressive strength  of  750  Ib.  per  sq.  in.,  at  28  days,  the  working  stresses 
shall  not  exceed  the  following: 

Bearing    225  Ib.  per  sq.  in. 

Compression   in   extreme   fiber 185    "       " 

Shear    25    "       "         " 

Bond    30    "       " 

WORKING  STRESSES  ON  REINFORCED  COLUMNS. 

30.  For  axial  compression  on  concrete  in  columns  reinforced  against 
buckling,  the  same  working  stresses  as  those  recommended  for  bear- 
ing may  be  used.     If  in  columns  reinforced  against  buckling  the  re- 
inforcement is  tied  together,  so  that  the  concrete  may  be  considered 
as  restrained  similarly  to  concrete  enclosed  in  a  steel  tube,  the  working 
strain  on  the  concrete  may  be  increased  to  35%   of  its  compressive 
strength,  or  approximately  700  Ib.  per  sq.  in.  for  2  000  Ib.  concrete. 

*  Compression  applied  to  a  surface  of  concrete  larger  than  the  leaded  area,  such  as 
the  pressure  on  bed-plates. 


35 


DETAILS  OF  CONSTRUCTION. 

31.  The  specifications  for  the  design  of  structural  steel  work  shall 
also  apply  to  the  steel  reinforcement  of  concrete  construction. 

32.  Plain  concrete  columns  may  be  used,  if  the  ratio  of  length  to 
the  least  side  or  diameter  does  not  exceed  12,  without  any  reduction 
in  the  working  stress  specified  for  axial  compression. 

33.  The  reinforcement  of  columns  shall  consist  of  shapes  which  can 
resist  compression.      These  shapes  shall  be  rigidly  connected  by  lat- 
tice bars  or  tie-plates  at  proper  intervals,  so  as  to   form  a  skeleton 
column.    Only  such  columns  shall  be  considered  as  reinforced. 

34.  The  reinforcement  should  be  provided  with  proper  connections 
between  the  bars  to  hold  them  in  the  right  place  and  at  the  correct 
distance  from    the  nearest  face  of  the  concrete,  so  as  to  prevent  dis- 
lodgment  during  the  depositing  and  compacting  of  the  concrete. 

35.  If  the  reinforcement  consists  of  round   or  square  bars,  their 
lateral  spacing  should  not  be  less  than  1£  diameters,  center  to  center; 
nor  should  the  distance  from  the  side  of  the  beam  to  the  center  of  the 
nearest  bar  be  less  than  2  diameters. 

36.  When  the  beam  or  slab  is  continuous  over  its  support,  rein- 
forcement should  be  provided  at  points  of  negative  moment. 

37.  In  connections  between  members,  such  as  between  columns  and 
girders,  and  girders  and  beams,  the  reinforcements  of  the  connecting 
members  shall  be  firmly  attached  to  each  other. 

38.  The  concrete  outside  of  the  reinforcement  is  not  to  be  con- 
sidered as  carrying  any  load. 

39.  Plain  concrete  walls,  if  made  of  concrete  which  will  develop  an 
average  compressive  strength  of  at  least  1  500  Ib.  per  sq.  in.  after  28 
clays,  may  be  of  the  same  thickness   as  brick  walls  laid  in  cement 
mortar.     If  properly  reinforced  in  both  directions,  the  thickness  may 
be  reduced  to  two-thirds  of  that  of  brick  walls.     Spandrel  and  curtain 
walls  of  steel  skeleton  construction  shall  have  a  minimum  thickness 
of  8  in.  if  reinforced  with  not  less  than  f  Ib.  of  steel  per  sq.  ft.  of 
wall.      Partitions,   if   constructed   of   reinforced   concrete,   shall   have 
a  minimum  thickness  of  3  in.,  and  shall  be  reinforced  with  not  less 
than  ^-in.  rods  on  12-in.  centers,  running  both  vertically  and  horizon- 
tally.    The  filling  of  panels  of  the  skeleton  frames  of  sheds  or  mill 
buildings  shall  not  be  less  than  4  in. 


Steel  Work. 


Plain 

Concrete 

Columns. 


Column 
Reinforce- 
ment. 


Beam 
Reinforce- 
ment. 


Continuous 
Beams  and 
Slabs. 

Connections 

Between 

Members. 


Walls. 


36 

Fireproofing.  40.  In  plain  coiac*ete  columns,  the  concrete  to  a  depth  of  1£  in. 
may  be  considered  as  protective  covering,  and  should  not  be  included 
in  the  effective  section.  Under  ordinary  conditions,  the  concrete 
covering  over  the  metal  reinforcement  in  office  buildings,  hotels  and 
similar  structures  should  be  at  least  2  in.  for  girders  and  columns,  li 
in.  for  beams,  and  1  in.  for  floor  slabs.  In  stores,  warehouses  or  other 
buildings  where  combustible  materials  are  likely  to  be  stored,  the  thick- 
ness of  the  protection  should  be  increased  to  3  or  4  in. 


Stone 
Concrete. 


Cinder 
Concrete. 


Portland 
Cement. 


Pine 
Aggregate. 


MATERIALS  AND  WORKMANSHIP. 

41.  Stone  or  gravel  concrete  shall  be  used  in  the  construction  of 
girders  and  columns,  or  any  other  parts  which  carry  loads  or  constitute 
integral  parts  of  the  structure. 

42.  Cinder  concrete  may  be  used  for  fireproofing,  for  floor  slabs 
and  for  parts  which  do  not  carry  any  loads,  such  as  curtain  walls, 
spandrel  walls,  parapet  walls,  partitions  and  filling  of  panels  of  steel 
skeletons  of  sheds  or  mill  building. 

43.  Only  Portland   cement  conforming   to   the  standard  specifica- 
tions of  the  American  Society  for  Testing  Materials  shall  be  used  in 
reinforced  concrete  work. 

AGGREGATES. 

44.  Extreme  care  should  be  exercised  in  selecting  the  aggregates 
for  mortar  and  concrete,  and  careful  tests  made  of  the  materials  for 
the  purpose  of  determining  their  qualities  and  the  grading  necessary  to 
secure  maximum  density*  or  a  minimum  percentage  of  voids. 

45.  Fine  aggregate  consists  of  sand,  crushed  stone,  or  gravel  screen- 
ings, passing  when  dry  a  screen  having  £-in.  diameter  holes.    It  should 
be  preferably  of-silicious  material,  clean,  coarse,  free  from  vegetable 
loam  or  other  deleterious  matter. 

46.  A  gradation  of  the  grain  from  fine  to  coarse  is  generally  ad- 
vantageous. 

47.  Mortars  composed  of  one  part  Portland  cement  and  three  parts 
fine  aggregate  by  weight  when  made  into   brique-ttes  should  show   a 
tensile  strength  of  at  least  70%  of  the  strength  of  1 :  3  mortar  of  the 
same  consistency  made  with  the  same  cement  and  standard  Ottawa 
sand. 

*  A  convenient  coefficient  of  density  is  the  ratio  of  the  sum  of  the  volumes  of  materials 
contained  in  a  unit  volume  to  the  total  unit  volume. 


37 


Coarse 
Aggregate. 


48.  Coarse   aggregate  consists  of  4«ect  onaterial,  such   as   crushed 
stone  or  gravel,  which  is  retained  on  a  screen  having  ^-in.  diameter 
holes.    The  particles  should  be  clean,  hard,  durable,  and  free  from  all 
deleterious  material.    Aggregates  containing  soft,  flat  or  elongated  par- 
ticles should  be  excluded  from  important  structures.     A  gradation  of 
sizes  of  the  particles  is  generally  advantageous. 

49.  The  maximum  size  of  the  coarse  aggregate  shall  be  such  that  it 
will  not  separate  from  the  mortar  in  laying  and  will  not  prevent  the 
concrete  from  fully  surrounding  the  reinforcement  and  filling  all  parts 
of  the  forms.    Where  concrete  is  used  in  mass,  the  size  of  the  coarse 
aggregate  may  be  such  as  to  pass  a  3-in.  ring.    For  reinforced  mem- 
bers a  size  to  pass  a  1-in.  ring,  or  a  smaller  size,  may  be  used. 

50.  Where  cinder  concrete  is  permissible,  the  cinders  used  as  the 
coarse  aggregate  should  be  composed  of  hard,  clean,  vitreous  clinker, 
free  from  sulphides,  unburned  coal,  or  ashes. 

51.  The  water  used  in  mixing  concrete  should  be  free  from  oil, 
acid,  strong  alkalis,  or  vegetable  matter. 

STEEL. 

52.  The  steel  used  for  reinforcement  shall  be  of  the  same  quality 
as   specified  for   structural   steelwork   in   buildings. 

53.  Steel  wire  used  for  reinforcement  should  be  drawn  from  rods 
of  basic  open-hearth  steel  of  the  same  quality  as  that  specified  for  rivet 
steel. 

54.  All  steel  to  be  embedded  in  concrete  shall  conform  to  the  shape 
and  sections  shown  on  drawings,  and  shall  be  delivered  unpainted.    It 
shall  be  thoroughly  cleansed  from  scale,  grease,  oil  and  rust,  and  given 
a  coating  of  Portland  cement  grouting  before  being  covered  with  con- 
crete.   The  cleaning  of  the  metal  shall  be  done  with  suitable  scrapers, 

steel  brushes   or  such  other  tools  as   may  most  efficiently   clean   the 
\ 

surface. 

CONCRETE. 

55.  The  materials  to  be  used  in  concrete  shall  be  carefully  selected, 
of  uniform  quality,  and  proportioned  with  a  view  to  securing  as  nearly 
as  possible  a  maximum  density. 

56.  The  unit  of  measure  shall  be  the  barrel,  which  should  be  taken    unit  of 
as  containing  3.8  cu.  ft.    Four  bags  containing  94  Ib.  of  cement  each 

shall  be  considered  the  equivalent  of  one  barrel.  Fine  and  coarse  ag- 
gregate should  be  measured  separately  as  loosely  thrown  into  the 
measuring  receptacle. 


Cinders. 


Quality  of 
Water. 


Quality  of 
Steel. 


Wire. 


Measure. 


38 


Relation  of 
Fine  and 
Coarse 
Aggregates. 
Relation  of 
Cement  and 
Aggregates. 


Mixing. 


Measuring 
Ingredients. 


Machine 
Mixing. 


Hand  Mixing. 


Consistency. 


Retempering. 


Placing  of 
Concrete. 


57.  The  fine  and  coarse  aggregates  shall  be  used  in  such  relative 
proportions  as  will  insure  maximum  density. 

58.  For  reinforced  concrete  construction,  a  density  proportion  based 
on  1 :  6  should  generally  be  used,  i.  e.}  one  part  of  cement  to  a  total 
of  six  parts  of  fine  and  coarse  aggregates  measured  separately. 

59.  In    columns,    richer    mixtures    are    often    required,    while    for 
massive  masonry  or  rubble  concrete  a  leaner  mixture,  of  1:9  or  even 
1 : 12,  may  be  used. 

60.  The  ingredients  of  concrete  should  be  thoroughly  mixed  to  the 
desired  consistency,  and  the  mixing  should  continue  until  the  cement 
is  uniformly  distributed  and  the  mass  is  uniform  in  color  and  homo- 
geneous,   since    the    maximum    density    and,    therefore,    the    greatest 
strength  of  a  given  mixture  depends  largely  on  thorough  and  complete 
mixing. 

61.  Methods  of  measurement  of  the  proportions  of  the  various  in- 
gredients, including  the  water,  should  be  used,  which  will  secure  sep- 
arate uniform  measurements  at  all  times. 

62.  When  the  conditions  will  permit,  a  machine  mixer  of  a  type 
which  insures  the  uniform  proportioning  of  the  materials  throughout 
the  mass  should  be  used,  since  a  more  thorough  and  uniform  consist- 
ency can  be  thus  obtained. 

63.  When  it  is  necessary  to  mix  by  hand,  the  mixing  should  be  on 
a  water-tight  platform,   and  especial  precautions  should  be  taken  to 
turn  the  materials  until  they  are  homogeneous  in  appearance  and  color. 

64.  The  materials  shall  be  mixed  wet  enough  to  produce  a  concrete 
of  such  a  consistency  as  will  flow  into  the  forms  and  about  the  metal 
reinforcement,  and,  at  the  same,  time,  can  be  conveyed  from  the  mixer 
to   the  forms   without  separation   of   the   coarse   aggregate   from   the 
mortar. 

65.  Retempering  mortar   or   concrete,   i.    e.,   remixing  with   water 
after  it  has  partially  set,  shall  not  be  permitted. 

66.  Concrete,   after  the  addition  of  water  to  the  mix,  should  be 
handled  rapidly,  and  in  as  small  masses  as  is  practicable,  from  the 
place  of  mixing  to  the  place  of  final  deposit,  and  under  no  circum- 
stances shall  concrete  be  used  that  has  partially  set  before  final  placing. 
A  slow-setting  Cement  should  be  used  when  a  long  time  is  likely  to 
occur  between  mixing  and  final  placing. 

67.  The  concrete  should  be  deposited   in   such   a  manner   as   will 
permit  the  most  thorough  compacting,   such   as   can   be   obtained  by 


39 


working  with  a  straight  shovel  or  slicing  tool  kept  moving  up  and 
down  until  all  the  ingredients  have  settled  in  their  proper  place  by 
gravity  and  the  surplus  water  has  been  forced  to  the  surface. 

68.  In  depositing  the  concrete  under  water,  special  care  should  be 
exercised  to  prevent  the  cement  from  being  floated  away,  and  to  pre- 
vent the  formation  of  laitance,  which  hardens  very  slowly  and  forms 
a  poor  surface  on  which  to  deposit  fresh  concrete.    Laitance  is  formed 
in  both  still  and  running  water,  and  should  be  removed  before  placing 
fresh  concrete. 

69.  Before  placing  the  concrete,  care  should  be  taken  to  see  that  the 
forms  are  substantial  and  thoroughly  wetted  and  the  space  to  be  occu- 
pied by  the  concrete  is  free  from  debris.    When  the  placing  of  the  con- 
crete  is   suspended,    all    necessary   grooves    for   joining   future   work 
should  be  made  before  the  concrete  has  had  time  to  set. 

70.  When  work  is  resumed,  concrete  previously  placed  should  be 
roughened,    thoroughly    cleansed    of    foreign    material    and    laitance, 
drenched  and  slushed  with  a  mortar  consisting  of  one  part  Portland 
cement  and  not  more  than  two  parts  fine  aggregate. 

71.  The  faces  of  concrete  exposed  to  premature  drying  should  be 
kept  wet  for  a  period  of  at  least  seven  days. 

72.  Concrete  for  reinforced  structures  should  not  be  mixed  or  de- 
posited at  a  freezing  temperature,  unless  special  precautions  are  taken 
to   avoid  the  use  of  materials   containing  frost  or  covered  with  ice 
crystals,  and  to  provide  means  to  prevent  the  concrete  from  freezing 
after  being  placed  in  position  and  until  it  has  thoroughly  hardened. 

73.  Where  the  concrete  is  to  be  deposited  in  massive  work,  its  value    Rubble 

Concrete, 
may  be  improved  and  its  cost  materially  reduced  through  the  use  of 

clean  stones  thoroughly  embedded  in  the  concrete  as  near  together  as 
is  possible  and  still  entirely  surrounded  by  concrete. 

74.  The  forms  must  have  sufficient  resistance  to  bending,  as  well  as 
to  shocks  and  vibrations  due  to  tamping,  and  they  shall  be  arranged 
to  be  safely  removable  while  their  supports  are  left  in  place.     The 
forms   should    be    as    nearly   watertight    as   possible,    to    prevent    the 
escaping  of  the  cement. 

75.  In   removing   the   forms   and   supports,    all   jar    and   vibration 
shall  be  avoided.     No  forms  shall  be  removed  except  in  the  presence 
of  the  inspector.    After  the  forms  are  removed,  no  patching  or  plaster- 
ing shall  be  done  until  all  surfaces  have  been  inspected  and  permis- 
sion given  by  the  engineer. 


Freezing 
Weather. 


Forms  and 
Supports. 


Removal 
of  Forms. 


40 

76.  The  period  which  must  elapse  between  the  completion  of  the 
tamping  and  the  removal  of  the  forms  is  a  matter  of  judgment  and 
depends  upon   the  weather,   the   distance  between   supports,   and   the 
weight  of  the  parts  of'  the  structure.     The  side  forms  of  beams  and 
columns,  and  the  forms  of  floor  slabs  up  to  spans  of  5  ft.  may  be  re- 
moved after  the  concrete  has  hardened  sufficiently,  that  is,  in  a  few 
days,  while  the  supports  of  beams  should  not  be  removed  in  less  than 
14  days.    For  longer  spans  and  larger  sections,  4  to  6  weeks  may  be 
necessary. 

77.  In    buildings    of    several    stories,    the    supports    of    the    lower 
floors  shall  not  be  removed  until  the  hardening  of  the  concrete  is  so 
far  advanced  that  it  can  safely  carry  the  load. 

Protection  78.  Immediately  after  the  completion  of  the  tamping,   the  struc- 

structure.  tural  parts  shall  be  protected  against  the  effect  of  freezing  and  pre- 
mature drying,  as  well  as  against  vibrations  and  loads,  until  the  con- 
crete is  sufficiently  hardened. 

INSPECTION  AND  TESTS. 

Facilities  for          79.  All  facilities  for  inspection  of  material  and  workmanship  shall 
Inspection. 

be  furnished  by  the  contractor  to  the  engineer  and  his  inspectors,  who 

shall  have  free  access  to  any  part  of  the  structure  during  construction, 
or  to  any  part  of  the  works  in  which  any  part  of  the  material  is  made. 
80.  Inspection  during  construction  shall  cover  the  following: 

a.  The  materials. 

b.  The   correct    construction    and   erection   of   the   forms    and 
supports. 

c.  The  sizes,  shapes  and  arrangement  of  the  reinforcement. 

d.  The  proportioning,  mixing  and  placing  of  the  concrete. 

e.  The  strength  of  the  concrete  by  tests  of  standard  test  pieces 
made  on  the  work. 

f.  Whether   the   concrete   is    sufficiently    hardened    before   the 
forms  and  supports  are  removed. 

g.  Prevention  of  injury  to  any  part  of  the  structure  by  and 
after  the  removal  of  the  forms. 

h.  Comparison  of  dimensions  of  all  parts  of  the  finished  struc- 
ture with  the  plans. 

Tests  of  81.  Samples  of  concrete  shall  be  taken  from  the  wheelbarrows  as  it 

Concrete. 

is  being  transported  to  the  forms  and  tested  in  8-in.  cylinders,  16  in. 
long,  to  ascertain  the  crushing  strength,  as  directed  by  the  engineer. 


41 


82.  All  steel  shall  be  tested  before  it  is  shipped  from  the  mills,  and 
all  manufactured  steel  work  inspected  in  the  shops  where  the  work  is 
being  done  before  shipment,  as  specified  for  structural  steel  work. 

83.  Load  tests  on  portions  of  the  finished  structure  shall  be  made 
where    there    is    reasonable    suspicion    that    the    work    has    not    been 
properly   performed,    or   that,   through   influences   of   some   kind,   the 
strength  has  been  impaired.     A  test  load  of  twice  the  live  load  shall 
cause  no  permanent  deformations.    Load  tests  shall  not  be  made  until 
after  60  days  of  hardening. 


Tests  of 
Steel. 


Load  Tests. 


42 


FORMULAS    FOE    APPROXIMATE    COMPUTATIONS 

RECOMMENDED  BY  THE  GERMAN 

CONCRETE   ASSOCIATION. 


SIMPLE    BENDING. 
1.  Rectangular  Beams. 
(a)  Reinforced  for  tension  only  (see  Fig.  1). 

If  A8  =  total  area  of  the  reinforcement,  in  sq.  in. 
b    — .  width  of  the  beam  in  inches. 

E.       I  15  for  stone  concrete, 
h  =  effective  depth,  n=  ~  =  j  30  for  cinder  concrete. 

M  =•  moment  of  the  exterior  forces,  in  inch-pounds. 
V  =  total  vertical  shear,  in  pounds. 
Distance  of  neutral  axis  from  top  of  beam 


x=  — -     — 


Max.  unit  stress  on  concrete  tf  = 


2  M 


Unit  stress  on  steel 6  = 


bx(ji- 
M 


^-1) 


Unit  shear 


43 


Unit  bond  stress  on  the  reinforcing  bars 


Sum  of  perimeters  of  all  bars 

A  computation  of  the  shear  and  bond  for  freely  supported  beams 
is  not  generally  necessary. 

(b)  With  double  reinforcement  for  tension  and  compression  (see 
Fig.  2). 

The  distance  of  neutral  axis  from  top  of  beam 


and  the  maximum  unit  compression  on  the  concrete 

6  MX 


bx*(3h—x)-\-6As  n(x  —  h')(h  —  h') 
Unit  stress  in  tension  in  the  lower  reinforcement 


Unit  stress  in  compression  on  the  upper  reinforcement 


2.  Beams  of  T  Section. 

The  effective  width  6  of  the  slab  is  to  be  assumed  as  b  ~^~  ^  Z,  where  I 
denotes  the  effective  length  of  the  beam;  b  should,  however,  not  be 
larger  than  the  distance  between  stems. 

For  T  beams,  two  cases  have  to  be  considered: 

(a)  When  the  neutral  axis  lies  in  the  slab,  or  x~^~  d  (see  Fig.  3). 


The  formulas  for  rectangular  beams  reinforced  for  tension  also 
apply  to  beams  of  T  section  when  the  shear  in  the  stem  and  the  bond 
in  the  reinforcement  over  the  supports  have  to  be  computed. 


44 


(&)  Where  the  neutral  axis  lies  in  the  stem,  or  x  >  cl   (see  Fig.  4). 


If  we  neglect  the  small  compression  in  the  stem  of  the  beam,  we 


get: 


2nhAs  +  bd2 


M 


and  6  =  — — - 

n  (ft  —  x) 


COMPEESSION. 

Columns  in  which  buckling  need  not  be  considered. 
(a)  Axial  pressure. 

If  Ac  denotes  the  area  of  the  concrete,  the  total  safe  load  on  the 
column 

P  =  <5C  (Ac  -f-  n  J.s),  where  n  =  15, 
and 

P  P 


(fc)  Eccentric  pressure  (bending  combined  with  axial  pressure). 

The  computations  can  be  made  in  the  same  manner  as  for  sections 
of  homogeneous  material  if,  in  the  areas  and  moments  of  resistance, 
the  section  of  the  reinforcement  is  added  to  that  of  the  concrete  with 
n  =  15  times  its  value.  If  tensile  strains  occur,  the  steel  reinforcement 
on  the  tension  side  must  be  able  to  resist  the  same. 


45 


APPENDIX. 


TABLE   1. — WEIGHTS  OF  BUILDING  MATERIALS,  ETC.,  IN  POUNDS 
PER  CUBIC  FOOT. 


Material.  Weight, 

Brick,  pressed  and  paving 150 

"     common  building 120 

"     soft  building 100 

Granite 170 

Marble 170 

Limestone  160 

Sandstone 150 

Cinders 40 

Slag 160-180 

Granulated  furnace-slag 53 

Gravel .  120 

Slate 175 

Sand,  clay  and  earth  (dry) 100 

"      "       "       (moist) 120 

Coal  ashes 45 

Paving  asphaltum '  100 

Plaster  of  Paris , 140 

Glass 160 

Water 62£ 

Snow,  freshly  fallen 10 

'•     wet 50 

Spruce 25 


Material.  Weight. 

Hemlock 25 

White  pine 25 

Douglas  fir 80 

Yellow  pine 40 

White  oak 50 

Mortar 100 

Stone  concrete 150 

Cinder       "        '. 110 

Common  brick  work 100-120 

Rubble  masonry,  sandstone 180 

limestone 140 

granite 150 

Ashlar  '  sandstone 140 

limestone 150 

granite 165 

Masonry  debris 90 

Cast  iron 450 

Wrought  iron 480 

Steel 490 

Lead 711 

Copper,  rolled 490 


Plaster,  ceiling.  10  to  15  Ib.  per  sq.  ft. 

TABLE  2. — WEIGHTS  OF  MERCHANDISE,  ETC.,  STORED  LOOSE  IN  HEAPS 
OR  TANKS,  IN  POUNDS  PER  CUBIC  FOOT. 


Alcohol 52 

Apples 47 

Barley 40 

Beans 55 

Beets . , 40 

Books 40 

Canned  Goods 45 

Cement,  natural 50-70 

Portland ...90-100 

Chalk 156 

Charcoal 15-30 

Cheese 30 

Coal,  soft 50 

"  hard....  55 

Coke 30-50 

Cork 15 

Corn 88 

Cotton  Goods 40 

Fat 58 

Flour 50 

Gunpowder 60 

Gypsum 60-70 

Hay,  loose.  . .  5 

"  baled 20 

Ice 55 

Lard 59 

Leather  Goods...  20 


Lime 60-80 

Naphtha 50 

Oats 30 

Oils 55 

Paper 35-60 

Peat,  dry,  unpressed 20-30 

Petroleum 55 

Pitch 75 

Potatoes 45 

Pumice  Stone 56 

Rags 20-45 

Rosin 68 

Rubber  Goods ...60-100 

Salt,  solid 134 

"   coarse 65 

"   fine  table 80 

Straw 10-20 

Sugar 50 

Sulphur 125 

Tallow 59 

Tar 75 

Tin,  cast 462 

"   in  boxes 278 

Wheat 50 

Wines 62 

Woolen  Goods  . .  25 


If  stored  in  bags,  barrels,  cases  or  boxes,  multiply  above  given  weights  by   0.8,  but 
take  outside  rectangular  dimensions. 


40 


TABLE  3. — PERMISSIBLE  COMPRESSIVE  STRESSES  FOR  STEEL, 

P  =  Stress  allowed  in  Ib.  per  sq.  in. 
I  =  Length  in  inches. 
r  =  Least  radius  of  gyration,  in  inches. 

P  =  16  000  —  70  I 


I 

r 

P 

I 
r 

P 

I 
r 

P 

I 
r 

P 

28 

14  000 

60 

11  800 

92 

9  560 

124 

7  820 

80 

13  900 

62 

11  660 

94 

9  420 

126 

7  180 

32 

13  760 

64 

11  520 

96 

9  280 

128 

7  040 

34 

13  620 

66 

11  380 

98 

9  140 

180 

6  9)0 

36 

13  480 

68 

11  240 

100 

9  000 

132 

6  760 

38 

13  340 

70 

11  100 

102 

8860 

134 

6  620 

40 

13  200 

72 

10960 

104 

8  720 

136 

6  480 

42 

13  060 

74 

10  820 

106 

8  580 

138 

6  340 

44 

12  920 

76 

10680 

108 

8  440 

140 

6  200 

46 

12780 

78 

10  540 

110 

8  300 

142 

6  060 

48 

12  640 

80 

10400 

112 

8  160 

144 

5  920 

50 

12500 

82 

10  260 

114 

8  020 

146 

5  780 

52 

12  860 

84 

10  120 

116 

7  880 

148 

5  640 

54 

12220 

86 

9  980 

118 

7  740 

150 

5  500 

56 

12  080 

88 

9840 

120 

7  600 

58 

11  940 

90 

9  700 

122 

7  460 

47 


•R 


a  aiss 


O        TH        CO 


»o      co      t- 


10         J>         05 


£.2  3* 

^  §r.s 


0        0       0 


o     d     d     o     d     TH 


^, 


48 


TABLE  5. — MAXIMUM  BENDING  MOMENTS  ON  PINS. 
Extreme  Fiber  Stress  of  24000  Lb.  per  Sq.  In. 


Dia.  of  pin, 
in  inches. 

Area  of  pin, 
in  sq.  in. 

Moments,  in 
inch-pounds. 

Dia.  of  pin, 
in  inches. 

Area  of  pin, 
in  sq.  in. 

Moments,  in 
inch-pounds. 

2 

8.142 

18  850 

6£ 

33.183 

647  070 

3.547 

22  610 

6| 

34.472 

685  120 

2£ 

3.976 

26  840 

63 

35.785 

724  640 

2jj 

4.430 

31  560 

6g 

37.122 

765650 

2i 

4.909 

86  820 

7 

38.485 

808  170 

2| 

5.412 

42  620 

7£ 

39.871 

852  250 

2? 

5.940 

49  000 

?s 

41.282 

897  890 

2| 

6.492 

55  990 

7| 

42.718 

945  140 

3 

7.069 

63  620 

7i 

44.179 

994  020 

BJ 

7.670 

71  910 

71 

45.664 

1  044  550 

3 

8.296 

80  880 

7! 

47.173 

1  096  770 

3 

8.946 

90  580 

77 

48.707 

1  150  700 

3 

9.621 

101  020 

8 

50.265 

1  206  370 

8 

10.321 

112  240 

8£ 

51.849 

1  263  810 

3 

11.045 

124  250 

8 

53.456 

1  3*3  040 

3 

11.793 

137  100 

i 

55.088 

1  384  090 

4 

12.566 

150  800 

I 

56.745 

1  447  000 

i 

13.364 

165  380 

8: 

58.426 

1  511  780 

4 

14.186 

180  870 

8 

60.132 

1  578  470 

4, 

15.033 

197  310 

8; 

61.862 

1  647  080 

4i 

15.904 

214  710 

9 

63.617 

1  717  660 

4 

16.800 

233  100 

9£ 

65.397 

1  790  230 

1 

17.721 

252  520 

! 

67.201 

1  864  820 

4 

18.665 

272  980 

9i 

69.029 

1  941  360 

5 

19.635 

294  520 

9 

70.882 

2  020  140 

20.629 

317  170         , 

9; 

72.760 

2  100  940 

51 

21.648 

340  950 

8 

74.662 

2  183  860 

5| 

22.691 

365  890 

9£ 

' 

76.590 

2  268  940 

H 

23.758 

392  010 

10 

78.54 

2  356  190 

si 

24.850 

419  350 

10£ 

82.52 

2  537  360 

s| 

25.967 

447  930 

io| 

86.59 

2  727  590 

si 

27.109 

47?  790 

10! 

90.76 

2  927  090 

6 

28.274 

508  940 

11 

95.03 

3  136  090 

1 

29.465 
30.680 

541  410 
575  240 

11* 
"I 

99.40 
103.87 

3  354  810 
3  583  480 

6f 

31.919 

610  450 

12 

113.10 

4  071  500 

TABLE  6. — THICKNESS  OF  SPRUCE  AND  WHITE  PINE  PLANK 
FOR  FLOORS. 


THICKNESS  OF  PLANK  IN  INCHES  FOR  VARIOUS  LOADS  PER  SQ.  FT. 


Span  in  feet. 

lb. 

30 

lb. 

40 

lb. 

50 

lb. 

75 

lb. 

100 

lb 

19.5 

lb. 

150 

lb. 

175 

lb. 

200 

lb. 
225 

lb. 

250 

lb. 
275 

lb. 

300 

lb. 
325 

lb. 

350 

lb. 

375 

lb. 

400 

4 
5 

0.9 

1  9 

1.1 
1  4 

1.2 
1  5 

1.5 

1  8 

1.7 
9,  1 

1.9 

9  4 

2.1 
9,  6 

2.2 

9,  8 

1.4 
3  0 

2.5 
3  9 

2.7 
3  4 

2.8 
3  5 

2.9 

3  7 

3.1 

3  8 

3.2 
4  1) 

3.3 
<\  1 

3.4 
4  8 

6 

7 

1.4 
1  7 

1.6 
1  9 

1.8 
9  1 

2.2 
9,  6 

2.6 
3  0 

2.9 
3  3 

3.1 

3  7 

3.4 
3  9 

3.6 
4  9 

3.8 
4  5 

4.0 
4  7 

4.2 
4  9 

4.4 
5  9, 

4.6 
5  4 

4.8 
*»  fi 

4.9 

5  8 

5.1 

5.9 

8 
9 

1.9 
9,  1 

2.2 

9,  5 

2  4 

9  7 

3.0 
3  4 

3.4 
3  9 

3.8 
4  3 

4.2 

4  7 

4.5 
5  1 

4.8 
5  4 

5.1 

5  8 

5.4 
6  1 

5.7 

5.9 

6.1 

.... 

10 

9  4 

9  7 

3  1 

3  7 

4  3 

4  8 

"i  9, 

*)  •) 

6  0 

11 

9,  6 

3  0 

3  4 

4  1 

4  7 

5  3 

5  8 

12 

9  9 

3  8 

3  7 

4  5 

5  9 

13 

3  1 

3.6 

4  0 

4  9 

5  6 

... 

14 

3  4 

3  9 

4  3 

5  3 

6  1 

For  Yellow  Pine  use  nine-tenths  of  the  above  thickness. 


40 

TA£>LEI    7 


STANDARD  DIMENSIONS  TOR  COLUMNS 


in 


\   5k 


Sfe 


A 


•a 


(p 


6k" 


a 


16 


15'CHANNELGOLUMNS 

WITH 


4  I  4 


14" 


e"CHANNEL  COLUMNS 

WITH  14 <$IG  Cov.  Pi_e>. 


Q 


^ 


i 


12" 


IO"CHANNEL  COLUMNS 

WlTHl2"<&l4CcV.Fls. 


c 


12" 


£r 


12 


oo 


10" 


s 

p 
b 


_ 
10 


9"CHANNELGOLUMNe> 

WITH  ioX  12  Cov.  PLS. 


la  BE  USED  ONLYWHEM 
UNAVOIDABLE 

'CHANNEL  COLUMNS 

WITH  id  ,5£  Cov.F\.e>. 


PLATE  3  ANGLE 
COLUMNS 


50 

TABLE  8 


STANDARD  FRAMING  OF  BEAMS 


2,4" 


£0 


IS" 


WEIGHT  41  LBS. 


2.  LS  4*4x^x1-3" 
WEIGHT  34L-B3. 


15 


WEIGHT  29  LB&. 


WEIGHT  2aLsa  WEIGHT  15  LBS 


e" 


WEIGHT 


21*6*4*^x0-2" 

WEIGHT  <s  LBS 


AMERICAN  BRIDGE  .  Co.  STANDARD  CAST  IRON  SEPARATORS 


.c.. 


ft)R6TDIOl9 


SIZE 

IHCHES 


20 


WEIGHT 

PERFt. 

Fbuwos 


80 


65 


55 


42 


25 


21 


18 


15 


!2'/4 


6 


OufTbOi/r 
-FLAMOES 

INCHES 


15 


II 


10 


AND  BOOS 


ICTAL 


52.3 


24.2 


15.0 


11.9 


8.4 


6.3 


5.2 


5.2 


5.2 


NCREA5E|n 

WEIGHT  OF 

SCPARATOP 


BEAM 


DISTANCE 

C.ToC. 
OFBEAM5 


3.6 


2.9 


2.5 


.6 


1.3 


6 


.9 


.7 


10 


II 


WEIGHT 
OFRPE: 
AND  BOLT 


i. a 


1.4 


1.9 


2.2, 


2.5 


2.7 


3.2 


3.5 


CAST  WA5HER5 


13 


4.0 


BOLT 


D. 


WEIGHT 


4.2. 


.41 


4.0 


IS 


5.3 


.o 


WEIGHTS  GIVEN  ARE  FOR 

!'* PIPE.  AND  ^BoiT 


51 


STANDARD        DETAILS 


GOVERNMENT  ANCHOR 


WEIGHT  5s**1 


ANGLE   ANCHOR 


-y 


ANGLES 
SHIPPED  LOOSE 


2 

I  BOLT  W+ 

WEIGHT  WITH  DOLT/* 


BUILT  IN  ANCHOR  BOLTS 


SWEDGE:  Bocre 


WHEN  DOLTS  ARE^ER^RATED  LESS  THAN 

WlDTHOFWtfhER  USE  DASHER  WmiTWO  HOLES 


DAM 
INCHES 

LENGTH 
Pn^lwa 

WEIGHT 

NCLUPING 

NUT-  Lea 

£ 

c« 

2 

% 

l'-o" 

3 

1 

l-o" 

4- 

[5 

I1-  3" 

7 

PURLIN  CONNECTIONS 


ANGLE  RJRLI  MS 


LEQH 


2x2. 


3x2^2 


GLIPA«GLC 


4x5 
4x3 


^  'e'^io"  CHANNELS 
]     15  HAVE  FLANGE  ALSO 
ArrACHEDlb  RAFTERS 


I       I 


52 


TABLE  10.— PLATE  GIRDERS. 
Tension  16  000  Lb.  per  Sq.  In.  Net.  Area. 


Each  flange  2  angles. 

Web  plate. 

Weight  per  ft. 

Maximum 
moments,   thou- 
sands of  ft.  Ibs. 

3  X  2£  X  A                 

24  X  i 

38  4 

90 

31  V  24-  X  i  . 

24  X  i 

40  0 

99 

31  X  2A  X    5 

SOX  I 
30  X  £ 

45.1 
49  9 

132 

154 

4  x  3  X  A    . 

'  30  X  £ 

54  3 

177 

5  X  31  X   -t 

36  X   ] 
36  X  £ 

59.4 
65  4 

222 
265 

5  X  3£  X  f  

42  X  i 
36  X  ^ 

70.5 
79  8 

320 
318 

6  X  4  X  £ 

42  X  A 

48  X  A 
36  X  A 

86.2 
92.6 

87  4 

385 
457 
367 

6  X  4  X  X 

42  X  A 
48.  X  A 
36  X  T5 

93.8 
100.2 
95  4 

443 
524 
415 

\J     S\    1     S\     Y^r     . 

6  X  4  X  i  

42  X  A 
48  X  A 
36  X  A 

101.8 
108.2 
103.0 

500 
589 
462 

6  X  4  X  | 

42  X  A 
48  X  A 

60  X  A 
36  X    3 

109.4 
115.8 

128.6 
125  9 

555 
652 

856 
565 

6  X  0  X  £ 

42  X   } 

48  X   f 
60  X  f 
36  X   f 

133.6 
141.2 
156.6 
124  3 

679 
797 
1  046 
544 

6X6X| 

48  X  | 
60  X  f 
•36  X  * 

139.6 
155.0 
142  7 

774 
1  023 
652 

6  X  6  X  a 

48  X  f 
60  X   | 
36  X  f 

158.0 
173.4 
176  0 

923 
1  211 

781 

48  X  f 
60  X  | 

72  X  | 

176.0 
191.4 
206.6 

1  066 
1  393 
1  739 

53 


TABLE  11. — WEIGHTS  OF  KOOF  TRUSSES  AND  PURLINS  FOR 

UNIFORM  LOADINGS. 
Weight  of  Trusses. 

PL 


W  — 


300  +  6  L  + 


P  D 


in  which 

W  =  weight  of  truss  per  square  foot  of  building; 

L  =  span  of  truss  in  feet; 

D  =  distance  center  to  center  of  trusses  in  feet; 

P  =  load  per  square  foot  on  truss. 
Weight  of  Purlins. 

D      1 


45  4  ' 

in  which 

Wl  =  weight  of  purlins  per  square  foot  of  building; 
D    =  distance  center  to  center  of  trusses  in  feet; 
P1  =  load  per  square  foot  on  purlins. 


TABLE  12.— TYPICAL  HAND  CRANES. 


Capacity 
in  tons. 

Span. 

Wheel  base. 

Maximum 
wheel 
load  in 
pounds. 

Side 
clear- 
ance. 

Vertical 
clearance. 

WEIGHT  OP  RAIL  POR: 

Plate  Girders. 

Beams. 

2 

30 
50 

4  ft.  0  in. 
5  "   0  kl 

3100 
4000 

7  in. 

7    k- 

4  ft.  0  in. 

4  '•  0  kk 

30  Ibs.  per  yd. 

30           u 

30 
30 

4 

30 
50 

4  "    0  " 
5  "    0  " 

5400 
6500 

8    " 
8    " 

4  "  6  '• 

4  "  0  " 

30 
30 

80 
30 

6 

30 
50 

6  kl    0  " 

7  "    0  " 

8000 
9200 

9    •* 
9    " 

5  ft.  0  " 

5  kk  0  " 

35 

35            " 

80 

80 

8 

30 
50 

6  "    0  •• 

7  "    0  " 

10500 
11800 

10   " 
10    " 

5   "  0  " 
5  "  0  " 

40            '• 
40 

35 
35 

10 

30 

50 

7  "    0  " 
8  "   0  " 

13000 
14400 

10    " 
10    " 

5  kk  0  " 

5   "   6   " 

40 
40 

40 
40 

16 

30 
50 

7  k     0  " 
8  k     0  " 

20700 
22300 

10    " 
10    " 

5  "  6  " 
5   k"  6  " 

45           " 
45 

45 
45 

20 

30 
50 

7  '     0  " 
8  '     0  " 

26000 
28000 

10    " 
10    ik 

5   kk  6  " 
5   kl   6  tk 

50           " 
50 

50 
50 

25 

30 
50 

7  '     0  " 
8  '     0  kk 

82300 
35000 

12    " 
12    kt 

6   k'  0  •' 
6   "  0  '• 

55            " 
55 

50 

50 

54 


TABLE  13. — TYPICAL  ELECTRIC  TRAVELING  CRANES. 


Capacity, 
in  tons. 

i 

Wheel  base. 

(j    o 

Maximum 
wheel  load, 
in  pounds. 

Side 
clearance. 

Vertical 
clearance. 

WEIGHT  OF  RAIL  FOR  : 

Plate  girders. 

Beams. 

5 
10 
16 

23 
25 

30 
40 
50 
60 

60 
75 
100 
150 

40 
60 

40 
60 

40 
60 

40 
60 

40 
60 

40 
60 

40 
60 

40 
60 

40 
60 

80 

40 
60 

80 
40 
60 

80 
40 
60 

80 
40 
60 

80 

8  ft.  6  in. 

9  "  0    " 

9  "  0    " 
9  tk  6    " 

9  "  6    " 
10  "  0    " 

10   "  0    " 
10  "  6    " 

10  "  0    " 

10  "  6    " 

10  "  6    " 
11   "  0    " 

11   "  0    " 

12  "  0    " 

11   "  0    " 

12  "  0    " 

13  "  0    " 
14  "  0    " 
15  "  0    " 

12  000 
18  000 

19  000 
21  000 

25  000 
29  000 

33  000 
36  000 

40  000 
44  000 

48  000 
52  000 

64  000 
70000 

72  000 
80  000 

88  000 
94  000 
108  000 

44  000 

47  000 

51  500 
55  000 
60  000 

64  000 
83  000 
86  000 

89  000- 
130  000 
134  000 

139  000 

10  in. 

10  " 

10  " 

10  " 

10  •' 
10  " 

12  " 
12  " 

12  " 
12  " 

12  •' 
12  " 

12  " 
12  " 

14  " 
14  " 

16  " 
16  " 

16  •' 

16  t; 
16  " 

16  " 

16  " 
16  " 

16  " 
19  " 

19  " 

19  " 

20  '• 
20  '• 

•20  " 

6  ft.  0  in. 

6  "   0  " 

6  "  0  " 

6  "  0  k' 

7  "  0  tk 
7  "  0  " 

7  "  0  " 
7  "  0  " 

8  u  0   " 

8  "  0  " 

8  "  0  " 
8  "  0  " 

9  "  0  " 

9  "  0  " 

9  "  0  " 
9  "  0  -" 

9  "  0  t; 
9  "  0  " 
9  u  0   " 

10  "  6   'k 
10  u  6   " 

10  "  6  " 
12,  "  0  " 
12  "  0  " 

12  "  0  '• 
13  "  6  lk 
13  "  6  " 

13  '•  6   " 

16   "   0  " 
16  "   0  " 

16   "  0  lk 

40  Ib.  per  yd. 

40       " 

45 
45 

50 
50 

55 
55 

60 
60 

70        " 
70        "  . 

80        " 
80 

100 
109 

100 
100 
100 

100        " 
100 

100 
100 
100 

100        " 
100 
100        " 

100 
150        " 
150 

150 

40 
40 

40 
40 

50 
50 

50 
50 

50 
50 

60 
60 

60 
60 

60 
60 

M&A 



miim 

soeoac' 

-£14L$  l£L 

tieteo 



SUUUL 

M- 

Loads,  clearances,  etc.,  given  above  are  for  end  carriages  of  electric  cranes. 


55 


ABSTRACTS  FROM  THE  FOLLOWING  BUILDING  LAWS: 
City  Year. 

New   York 1906 

Chicago 1905 

Philadelphia 1907 

Baltimore   1908 

St.   Louis 1907 

Boston  1907 

Buffalo 1905 

San  Francisco 1907 

Milwaukee    1901 

District  of  Columbia 1902 

Minneapolis 1907 

Providence   1905 

Kochester   1904 

New  Haven • 1905 

In  the  following  tables: 

I    =  Unsupported  length,  in  inches ; 
Zx  =  Effective  "       " 

r    =  Corresponding  radius  of  gyration,  in  inches; 
d    =  Least  lateral  dimension,  in  inches; 
W    =  Total  load,  in  lb.,  uniformly  distributed. 


56 


TABLE 
MINIMUM  LIVE  LOADS  FOR 


] 

POUNDS  PER 

Structure. 

New  York, 
1906. 

Chicago, 
1905. 

Philadelphia 

1907. 

Baltimore, 
1908. 

.3 

|§ 

» 

fr 

Dwellings,       apartment       houses,  I 
hotels   etc                                        f 

.) 

Dwellings, 
apartment 
houses,  40  ; 

}•       70 

60 

60  j 

50 
For  room 
>  500 

Office  buildings  first  floor 

1 
I 

150 

hotels, 
etc.,  50. 

50 

J 

ioo 

150 

I 
150 

sq.  ft.,  100. 
100 

Office  buildings,  above  first  floor  — 

Public  assembly  rooms,  churches,  I 
theatres  etc  I 

75 
90 

50 
100 

100 
120     \ 

75 

75  with, 
125  with- 
out fixed 

70 

lioo 

100 
200 

Schools  or  places  of  instruction  

75 

75 

( 

seats. 
75 

J 
100  -{ 

Assembly 
rooms,  125; 

Machine    shops,     armories,     drill-  1 

( 

other 
rooms,  60. 

rooms,  etc  C 

Light    manufacturing    and    retail  j 
stores  and  storehouses  ] 

120,  not 
includ  • 

1-     100 

120 

125 

150 

125 

Heavy  storehouses,  warehouses  and  J 

chinery. 

150,  not 
includ- 

I     100 

150     •{ 

Factory, 
175  ; 
storage, 

f-150 

. 
250 

Stables  or  carriage  houses  

chinery. 

*'l 

J 

Area  <  500 
sq.  ft.,  40; 

( 
\ 

100 

j 

Stairways           

[ 

larger 
floors,  100. 

70 

Sidewalks  

300 

200 

Roofs,   per  square  foot  of  super-  j 

For 

slopes 

j 

30 

Roofs,  per  square  foot  of  horizontal  j 

<  20°,  50. 

For 

slopes 

1 

I      25 

I 

For 
slopes 

>  90°    20 

1    For 
1    flat 

(For  flat 

Wind,  per  square  foot  of  elevation..  . 

>  20°,  30. 

*\ 

j 

When     \ 
h't  is    j 

1 

35,  re- 
duced. 
See  Build- 

<20°, 40. 

u 

J     40. 
30 

{ 

=  li     1 
width,  30.  [ 

ing  Laws, 
pp.  32-33. 

1 

67 


14  A. 

FLOORS,  ROOFS,  AND  WALLS. 


SQUARE  FOOT. 


0- 

8      • 

.22 

6 

.. 

of 

fr 

iji 

® 

&     . 

II 

§ 

II" 

Minneapol 

1907. 

3g 

£ 

1 

SI 

t 

c3io 

Kg 
fc1^ 

0) 

fc 

Id 

is 

Dwellings, 
40  ;      apart 
houses,    ho- 
tels, etc.,  70 

]  First   floo 
\  150  ;    othe 
floors,  75. 

L         40 

Halls,   dining 
rooms,  offices 
etc.,  75;  other 
rooms,  50. 

j- 

f70ex 

}    » 

7 

(       40    * 

•<8  000    t 
I     500    t 

Halls      and  ] 

70 

150 

60 

Lobbies.  110; 
other    floor 

If. 

150 

70 

IOC 

(       80    * 
•{5  000    t 

space,  75.       j 

(tooo  j 

70 

75 

60 

do. 

7 

150 

70 

IOC 

(       50    * 

<5  000    t 

|l  000    t 

100 

125 

80 

110 

125 

125^ 

Theaters,    ) 

80 

120 

(     100    * 
•{5  000    t 

| 

others,    70  \ 

(l  000    % 

)100 

75 

50 

75 

100 

100 

70 

7 

(       60    * 
•J5  000    t 

|l  000    $ 

250 

250 

120 

120  ;  not  in- 
cluding ma- 
chinery. 

>•      100 

1 

110 

100 

150 

100 

150 

(       80    * 

-(8  000    t 
|l  000    J 

150 

250  ;  not  in 
eluding  ma- 

1 

200 

j 

150;  in-     1 

(   120up   * 

chinery. 

50j 

crease  for  > 
machinery-  ) 

•<  special   t 
(special   t 

j  Public,  120;  i 

n* 

( 

Pnhlio    100  • 

(       80    * 

1  Private,  40.  j 

75 

200 

85 

70] 

c  UOJ1C,  1UU  , 

Private,  50. 

-{8  000    j- 
(l  000    J 

r 

100  ;   lower 

i 
.; 

supports  to 
carry  two- 

i 

t  birds      of 

i 

total  wt, 

300 

SOO 

(       800    * 
J  jo  000    t 

I    1  000    % 

I 

"or  slopes    I 

30 

25 

50 

40 

Flat  roofs. 

i 

<•  20°,  50.      ( 

40    * 

2  000    t 

500    J 

f            ^O        \ 

"or   slopes  1 

30 

40 

slopes, 

<  20°,  30.      f 

special. 

r 

JO  at  twelfth 

,  When  h't  is 

jory. 

=  H   width, 

90        4 

>£  less  at 

30 

30 

30 

30    2 

\ 

ich  lower 

( 

tory. 

*  Uniform  load  in  pounds  per  square  foot  of  floor  area. 

t  Concentrated  load  in  pounds,  which  shall  be  applied  to  any  point  of  the  floor. 

J  Uniform  load,  in  pounds  per  linear  foot,  for  girders. 


O  PH 

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